[clang] [llvm] [OpenACC] Switch Clang to use the Flang 'appertainment' rules for cla… (PR #135372)

[Erich Keane via llvm-commits]

erichkeane wrote:

@clementval @razvanlupusoru 

This should now be ready, though it probably has to be merged with the flang changes after `num_gangs`/`num_workers`/`vector_length` changes are made.

MOST of this ended up being test changes as we went along, But the tablegen/ACC.td changes/etc are mostly what I want you guys to look at.  SemaOpenACCAppertainment.cpp is where all of the changes related to using ACC.td are located.

https://github.com/llvm/llvm-project/pull/135372