[flang] Merge pull request flang-compiler/f18#565 from flang-compiler/pmk-fixes

When creating symbols for intrinsics, do not put them in the global s…

Original-commit: flang-compiler/f18@38789942a74f83d38c1132e96708158738ae0784
Reviewed-on: https://github.com/flang-compiler/f18/pull/565