system-build.sh: Use a more accurate path to clang's libraries
system-build.sh: Use a more accurate path to clang's libraries

The path to clang libraries must respect the llvm-config= option,
also on RPM-based distros /lib and /lib64 are separate directories.

This patch assumes that clang is always installed in the same
manner as llvm is, otherwise it aborts the build.

staticafi/symbiotic,staticafi/symbiotic,staticafi/symbiotic,staticafi/symbiotic