[clang] [OpenMP][Clang] Parsing support for num_teams lower bound (PR #180608)

[Zahira Ammarguellat via cfe-commits]

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

Please fix diagnostic message. Otherwise looks good. Thanks.
Let's see if @alexey-bataev has additional comments.

https://github.com/llvm/llvm-project/pull/180608