Missing the compile flag `-fno-tree-vectorize` since version v1.4.7

**Describe the bug**
Hi, there. I am using makefile to build zstd on linux and gcc, using commands as follows. And i found the compile flag `-fno-tree-vectorize` is missing since version v1.4.7. To be more actually, since commit e8eb2939feb98c5dd425181247557b9c59649fca #2368 。
```
clear && make clean && make -n
```
The compile flag only applies to the source file `decompress/zstd_decompress_block.c`，and comes from pr #1668。It seems to be a perf optimization on gcc platform.
Here is the output build on commit e8eb2939feb98c5dd425181247557b9c59649fca, which missing the compile flag for perf optimization.
```
make -C ../lib libzstd.a
make[2]: Entering directory '/home/admin/workspace/zstd/lib'
mkdir -p obj/statlib
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/debug.c -o obj/statlib/debug.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/entropy_common.c -o obj/statlib/entropy_common.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/error_private.c -o obj/statlib/error_private.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/fse_decompress.c -o obj/statlib/fse_decompress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/pool.c -o obj/statlib/pool.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/threading.c -o obj/statlib/threading.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/xxhash.c -o obj/statlib/xxhash.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/zstd_common.c -o obj/statlib/zstd_common.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/fse_compress.c -o obj/statlib/fse_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/hist.c -o obj/statlib/hist.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/huf_compress.c -o obj/statlib/huf_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_compress.c -o obj/statlib/zstd_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_compress_literals.c -o obj/statlib/zstd_compress_literals.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_compress_sequences.c -o obj/statlib/zstd_compress_sequences.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_compress_superblock.c -o obj/statlib/zstd_compress_superblock.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_double_fast.c -o obj/statlib/zstd_double_fast.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_fast.c -o obj/statlib/zstd_fast.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_lazy.c -o obj/statlib/zstd_lazy.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_ldm.c -o obj/statlib/zstd_ldm.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_opt.c -o obj/statlib/zstd_opt.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstdmt_compress.c -o obj/statlib/zstdmt_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./decompress/huf_decompress.c -o obj/statlib/huf_decompress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./decompress/zstd_ddict.c -o obj/statlib/zstd_ddict.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./decompress/zstd_decompress.c -o obj/statlib/zstd_decompress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./decompress/zstd_decompress_block.c -o obj/statlib/zstd_decompress_block.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./deprecated/zbuff_common.c -o obj/statlib/zbuff_common.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./deprecated/zbuff_compress.c -o obj/statlib/zbuff_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./deprecated/zbuff_decompress.c -o obj/statlib/zbuff_decompress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./dictBuilder/cover.c -o obj/statlib/cover.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./dictBuilder/divsufsort.c -o obj/statlib/divsufsort.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./dictBuilder/fastcover.c -o obj/statlib/fastcover.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./dictBuilder/zdict.c -o obj/statlib/zdict.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./legacy/zstd_v05.c -o obj/statlib/zstd_v05.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./legacy/zstd_v06.c -o obj/statlib/zstd_v06.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./legacy/zstd_v07.c -o obj/statlib/zstd_v07.o
echo compiling static library
ar rcs libzstd.a obj/statlib/debug.o obj/statlib/entropy_common.o obj/statlib/error_private.o obj/statlib/fse_decompress.o obj/statlib/pool.o obj/statlib/threading.o obj/statlib/xxhash.o obj/statlib/zstd_common.o obj/statlib/fse_compress.o obj/statlib/hist.o obj/statlib/huf_compress.o obj/statlib/zstd_compress.o obj/statlib/zstd_compress_literals.o obj/statlib/zstd_compress_sequences.o obj/statlib/zstd_compress_superblock.o obj/statlib/zstd_double_fast.o obj/statlib/zstd_fast.o obj/statlib/zstd_lazy.o obj/statlib/zstd_ldm.o obj/statlib/zstd_opt.o obj/statlib/zstdmt_compress.o obj/statlib/huf_decompress.o obj/statlib/zstd_ddict.o obj/statlib/zstd_decompress.o obj/statlib/zstd_decompress_block.o obj/statlib/zbuff_common.o obj/statlib/zbuff_compress.o obj/statlib/zbuff_decompress.o obj/statlib/cover.o obj/statlib/divsufsort.o obj/statlib/fastcover.o obj/statlib/zdict.o obj/statlib/zstd_v05.o obj/statlib/zstd_v06.o obj/statlib/zstd_v07.o
make[2]: Leaving directory '/home/admin/workspace/zstd/lib'

make -C ../lib libzstd.a
make[2]: Entering directory '/home/admin/workspace/zstd/lib'
mkdir -p obj/statlib
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/debug.c -o obj/statlib/debug.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/entropy_common.c -o obj/statlib/entropy_common.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/error_private.c -o obj/statlib/error_private.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/fse_decompress.c -o obj/statlib/fse_decompress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/pool.c -o obj/statlib/pool.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/threading.c -o obj/statlib/threading.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/xxhash.c -o obj/statlib/xxhash.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./common/zstd_common.c -o obj/statlib/zstd_common.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/fse_compress.c -o obj/statlib/fse_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/hist.c -o obj/statlib/hist.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/huf_compress.c -o obj/statlib/huf_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_compress.c -o obj/statlib/zstd_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_compress_literals.c -o obj/statlib/zstd_compress_literals.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_compress_sequences.c -o obj/statlib/zstd_compress_sequences.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_compress_superblock.c -o obj/statlib/zstd_compress_superblock.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_double_fast.c -o obj/statlib/zstd_double_fast.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_fast.c -o obj/statlib/zstd_fast.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_lazy.c -o obj/statlib/zstd_lazy.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_ldm.c -o obj/statlib/zstd_ldm.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstd_opt.c -o obj/statlib/zstd_opt.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./compress/zstdmt_compress.c -o obj/statlib/zstdmt_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./decompress/huf_decompress.c -o obj/statlib/huf_decompress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./decompress/zstd_ddict.c -o obj/statlib/zstd_ddict.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./decompress/zstd_decompress.c -o obj/statlib/zstd_decompress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./decompress/zstd_decompress_block.c -o obj/statlib/zstd_decompress_block.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./deprecated/zbuff_common.c -o obj/statlib/zbuff_common.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./deprecated/zbuff_compress.c -o obj/statlib/zbuff_compress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./deprecated/zbuff_decompress.c -o obj/statlib/zbuff_decompress.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./dictBuilder/cover.c -o obj/statlib/cover.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./dictBuilder/divsufsort.c -o obj/statlib/divsufsort.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./dictBuilder/fastcover.c -o obj/statlib/fastcover.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./dictBuilder/zdict.c -o obj/statlib/zdict.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./legacy/zstd_v05.c -o obj/statlib/zstd_v05.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./legacy/zstd_v06.c -o obj/statlib/zstd_v06.o
cc -c -DXXH_NAMESPACE=ZSTD_ -DZSTD_LEGACY_SUPPORT=5 -O3 -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef -Wpointer-arith -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings -Wredundant-decls -Wmissing-prototypes -Wc++-compat ./legacy/zstd_v07.c -o obj/statlib/zstd_v07.o
echo compiling static library
ar rcs libzstd.a obj/statlib/debug.o obj/statlib/entropy_common.o obj/statlib/error_private.o obj/statlib/fse_decompress.o obj/statlib/pool.o obj/statlib/threading.o obj/statlib/xxhash.o obj/statlib/zstd_common.o obj/statlib/fse_compress.o obj/statlib/hist.o obj/statlib/huf_compress.o obj/statlib/zstd_compress.o obj/statlib/zstd_compress_literals.o obj/statlib/zstd_compress_sequences.o obj/statlib/zstd_compress_superblock.o obj/statlib/zstd_double_fast.o obj/statlib/zstd_fast.o obj/statlib/zstd_lazy.o obj/statlib/zstd_ldm.o obj/statlib/zstd_opt.o obj/statlib/zstdmt_compress.o obj/statlib/huf_decompress.o obj/statlib/zstd_ddict.o obj/statlib/zstd_decompress.o obj/statlib/zstd_decompress_block.o obj/statlib/zbuff_common.o obj/statlib/zbuff_compress.o obj/statlib/zbuff_decompress.o obj/statlib/cover.o obj/statlib/divsufsort.o obj/statlib/fastcover.o obj/statlib/zdict.o obj/statlib/zstd_v05.o obj/statlib/zstd_v06.o obj/statlib/zstd_v07.o
make[2]: Leaving directory '/home/admin/workspace/zstd/lib'

```

And build on commit 3e519be9656c586e2b80441929b1692adec21a9e which just before the commit e8eb2939feb98c5dd425181247557b9c59649fca, the compile flag is present.
And I also build on latest dev branch, still no `-fno-tree-vectorize` presents.

**To Reproduce**
```
git checkout 3e519be9656c586e2b80441929b1692adec21a9e
clear && make clean && make -n
```

**Expected behavior**
The compile flag should be present.

**Screenshots and charts**
If applicable, add screenshots and charts to help explain your problem.

**Desktop (please complete the following information):**
- OS: Linux 4.19.91
- Version: 1.4.7
- Compiler: gcc
- Flags:
- Other relevant hardware specs
- Build system: Makefile

gcc -v
```
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/6.5.1/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,objc,obj-c++,fortran,go,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --disable-libgcj --with-isl --disable-libmpx --enable-gnu-indirect-function --with-tune=generic --with-arch_32=x86-64 --build=x86_64-redhat-linux
Thread model: posix
gcc version 6.5.1 20181026 (GCC)
```

os info (hostname desensitized)
```
Linux v43c*****.s**.n**** 4.19.91-012.ali4000.alios7.x86_64 #1 SMP Wed Sep 15 17:27:09 CST 2021 x86_64 x86_64 x86_64 GNU/Linux
```