[clang] [flang] [llvm] [openmp] [Flang] Move builtin .mod generation into runtimes (Reapply #137828) (PR #171515)

[Michael Kruse via llvm-commits]

Meinersbur wrote:

The changes to the Clang driver implement looking for the new location of the module files. Committing either one without the other will result in those modules not being found.

https://github.com/llvm/llvm-project/pull/171515