libselinux: fix compiler flags for linux + clang

As reported by Nicolas Iooss, the clang + linux build seems
broken:

 clang-3.9: warning: argument unused during compilation: '-undefined
dynamic_lookup'
  /usr/bin/ld: unrecognised option: -install_name
  clang-3.9: error: linker command failed with exit code 1 (use -v to
see invocation)

We already have those options set for Darwin, just drop them from the
clang side.

Signed-off-by: William Roberts <william.c.roberts@intel.com>
1 file changed