Closed issue by dinama on void-packages repository

https://github.com/void-linux/void-packages/issues/19839

Description:
Can't prepare package which using clang for build because shell `common/environment/configure/hardening.sh` set ` "-fstack-clash-protection -D_FORTIFY_SOURCE=2"`  as  default CFLAGS. 

And  compilation broken:

```
FAILED: CMakeFiles/cmTC_a2b73.dir/testCCompiler.c.o     
/usr/lib/ccache/bin/clang   -fstack-clash-protection -D_FORTIFY_SOURCE=2 \
  -mtune=generic -O2 -pipe -o CMakeFiles/cmTC_a2b73.dir/testCCompiler.c.o \
    -c testCCompiler.c

    clang-9: error: unknown argument: '-fstack-clash-protection'
```

This workaround on <package>/template locally resolve this problem:

```
export CFLAGS=$(sed 's/-fstack-clash-protection//g' <<<$CFLAGS) 
export CXXFLAGS=$(sed 's/-fstack-clash-protection//g' <<<$CXXFLAGS)

```