[clang] [Clang][Sema][OpenMP] Allow `num_teams` to accept multiple expressions (PR #99732)

[Shilei Tian via cfe-commits]

shiltian wrote:

Ah, we don't even have an entry for `ompx_bare` in `OpenMPSupport.rst`. I will do a follow-up patch to add it there.

https://github.com/llvm/llvm-project/pull/99732