[19.07] crtmpserver does not compile with ccache

Maintainer: @heil
Environment: powerpc8540, mvebu (cortexa53, cortexa9), OpenWrt 19.07.
Description:

1. Download SDK (for example: openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64.tar.xz)
2. Extract it
3. Update and install feeds
4. In make menuconfig, in Advanced configuration options (for developers) select Use ccache
5. Compile crtmpserver

Description:

make[5]: Entering directory '/openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64/build_dir/target-powerpc_8540_musl/crtmpserver-b866fffca37c3b967a8878499cd2b91aa2587f34'
[  1%] Generating ../precompiled.gch/Release.c++/common.gch
/openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64/staging_dir/host/bin/ccache: invalid option -- 'O'
Usage:
    ccache [options]
    ccache compiler [compiler options]
    compiler [compiler options]          (via symbolic link)

Common options:
    -c, --cleanup             delete old files and recalculate size counters
                              (normally not needed as this is done
                              automatically)
    -C, --clear               clear the cache completely (except configuration)
    -F, --max-files=N         set maximum number of files in cache to N (use 0
                              for no limit)
    -M, --max-size=SIZE       set maximum size of cache to SIZE (use 0 for no
                              limit); available suffixes: k, M, G, T (decimal)
                              and Ki, Mi, Gi, Ti (binary); default suffix: G
    -p, --show-config         show current configuration options in
                              human-readable format
    -s, --show-stats          show summary of configuration and statistics
                              counters in human-readable format
    -z, --zero-stats          zero statistics counters

    -h, --help                print this help text
    -V, --version             print version and copyright information

Options for scripting or debugging:
        --dump-manifest=PATH  dump manifest file at PATH in text format
    -k, --get-config=K        print the value of configuration key K
        --hash-file=PATH      print the hash (<MD4>-<size>) of the file at PATH
        --print-stats         print statistics counter IDs and corresponding
                              values in machine-parsable format
    -o, --set-config=K=V      set configuration item K to value V

See also <https://ccache.dev>.
make[5]: *** [common/CMakeFiles/common_common_gch.dir/build.make:61: precompiled.gch/Release.c++/common.gch] Error 1
make[5]: Leaving directory '/openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64/build_dir/target-powerpc_8540_musl/crtmpserver-b866fffca37c3b967a8878499cd2b91aa2587f34'
make[4]: *** [CMakeFiles/Makefile2:183: common/CMakeFiles/common_common_gch.dir/all] Error 2
make[4]: Leaving directory '/openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64/build_dir/target-powerpc_8540_musl/crtmpserver-b866fffca37c3b967a8878499cd2b91aa2587f34'
make[3]: *** [Makefile:130: all] Error 2
make[3]: Leaving directory '/openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64/build_dir/target-powerpc_8540_musl/crtmpserver-b866fffca37c3b967a8878499cd2b91aa2587f34'
make[2]: *** [Makefile:91: /openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64/build_dir/target-powerpc_8540_musl/crtmpserver-b866fffca37c3b967a8878499cd2b91aa2587f34/.built] Error 2
make[2]: Leaving directory '/openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64/feeds/packages/multimedia/crtmpserver'
time: package/feeds/packages/crtmpserver/compile#4.54#0.86#6.60
make[1]: *** [package/Makefile:113: package/feeds/packages/crtmpserver/compile] Error 2
make[1]: Leaving directory '/openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64'
make: *** [/openwrt-sdk-19.07.2-mpc85xx-p2020_gcc-7.5.0_musl.Linux-x86_64/include/toplevel.mk:220: package/crtmpserver/compile] Error 2

Inspect the crtmpserver package under feeds/packages/multimedia/crtmpserver and its CMake-based build output. Reproduce the package compile with ccache enabled using the OpenWrt 19.07 SDK and trace the precompiled-header command that reaches ccache. Done means crtmpserver compiles successfully with ccache enabled.