cmake OPENMP_HAVE_WALL_FLAG examples

Lewuathe/mlir-hello thirdparty/llvm-project/openmp/cmake/config-ix.cmake :19 

check_cxx_compiler_flag(-Wall OPENMP_HAVE_WALL_FLAG)

llvm-mirror/openmp cmake/config-ix.cmake :3 

check_cxx_compiler_flag(-Wall OPENMP_HAVE_WALL_FLAG)