[clang] [analyzer] Recognize missing MPI collectives in MPI-Checker (PR #209263)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat commented:

This passes my vibe check, but I'm completely unfamiliar with MPI and didn't look too closely for small issues.

I support merging this commit (especially since it only affects a single optin chekcer) but I don't think that I'm qualified to give a formal approval.

https://github.com/llvm/llvm-project/pull/209263