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

[Michael Klemm via cfe-commits]

https://github.com/mjklemm requested changes to this pull request.

Please address @saiislam's questions.  I also think that the title and description of the PR should reflect that this PR not only introduces the 6.0 flag, but also moves several of the tests to test against 5.1 and 6.0. 

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