[clang] [OpenMP] Allow OMP6.0 features. (PR #122108)

[Saiyedul Islam via cfe-commits]

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

Thank you for sticking up with this patch @zahiraam.
It mostly looks ok to me, but please wait for @mjklemm and @Meinersbur reviews.

https://github.com/llvm/llvm-project/pull/122108