[clang] [CIR][NFC] Fix Missing Decl::OMPGroupPrivate warning (PR #159631)

[Bruno Cardoso Lopes via cfe-commits]

https://github.com/bcardosolopes approved this pull request.

LGTM with one change: seems like https://github.com/llvm/llvm-project/pull/159694 is doing it wrong (shouldn't be a NYI), can you rebase and just move what it added to the path you add here? Thanks

https://github.com/llvm/llvm-project/pull/159631