cmake LIBOMP_HAVE_MRTM_FLAG examples

Lewuathe/mlir-hello thirdparty/llvm-project/openmp/runtime/cmake/config-ix.cmake :84 

check_cxx_compiler_flag(-mrtm LIBOMP_HAVE_MRTM_FLAG)

llvm-mirror/openmp runtime/cmake/config-ix.cmake :73 

check_cxx_compiler_flag(-mrtm LIBOMP_HAVE_MRTM_FLAG)