ARM64 ERROR: Cannot build on OpenWRT

error on OpenWrt 21.02-RC3 on a ARM64 board...

# python3 --version
Python 3.9.6

  ERROR: Failed building wheel for zstandard
...
Failed to build zstandard
ERROR: Could not build wheels for zstandard which use PEP 517 and cannot be installed directly
...

trying to install with :

pip download --no-deps zstandard
tar -zxf zstandard-0.15.2.tar.gz
cd zstandard-0.15.2
python3 setup.py build
python3 setup.py install

get error on build :

root@ultra:~/zstandard-0.15.2# python3 setup.py build 
generating build/zstandard/_cffi.c
(already up-to-date)
not modified: 'build/zstandard/_cffi.c'
running build
running build_py
running build_ext
building 'zstandard.backend_c' extension
gcc -Wno-unused-result -Wsign-compare -DNDEBUG -Os -pipe -mcpu=cortex-a53 -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -ffile-prefix-map=/builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/Python-3.9.6=Python-3.9.6 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro -Os -pipe -mcpu=cortex-a53 -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -ffile-prefix-map=/builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/Python-3.9.6=Python-3.9.6 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro -DNDEBUG -fno-inline -Os -pipe -mcpu=cortex-a53 -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -ffile-prefix-map=/builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/Python-3.9.6=Python-3.9.6 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro -DNDEBUG -fno-inline -I/builder/shared-workdir/build/sdk/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/usr/include -I/builder/shared-workdir/build/sdk/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/include/fortify -I/builder/shared-workdir/build/sdk/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/include -fPIC -Ic-ext -Izstd -I/usr/include/python3.9 -c c-ext/backend_c.c -o build/temp.linux-aarch64-3.9/c-ext/backend_c.o -DZSTD_SINGLE_FILE -DZSTDLIB_VISIBILITY= -DZDICTLIB_VISIBILITY= -DZSTDERRORLIB_VISIBILITY= -fvisibility=hidden
gcc: error: unrecognized command line option '-ffile-prefix-map=/builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/Python-3.9.6=Python-3.9.6'
gcc: error: unrecognized command line option '-ffile-prefix-map=/builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/Python-3.9.6=Python-3.9.6'
gcc: error: unrecognized command line option '-ffile-prefix-map=/builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/Python-3.9.6=Python-3.9.6'
error: command '/usr/bin/gcc' failed with exit code 1

Start with setup.py and c-ext/backend_c.c, then reproduce the setup.py build on the reported OpenWrt ARM64 environment while examining the compiler invocation. Done means the zstandard extension builds and installs successfully without the reported compiler failure.