[clang] [OpenMP] Change default version to OMP6.0. (PR #122108)

[Michael Klemm via cfe-commits]

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

The PR seems to have two components:

1) Upgrade the compiler code to be able to accept OpenMP 6.0 features
2) switch the default to be OpenMP 6.0

Part 1 is fine, as the community is starting to implement 6.0 features and, therefore, we need the compiler to understand the notion of that new version.

Part 2 should be removed from this PR.  If users want OpenMP 6.0 features they can specifically request that version via the command line (as Part 1 adds this).  The default version should stay with 5.1 at this point until a reasonable fraction of OpenMP 6.0 has been implemented that warrants switching.  At this point this is not the case.

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