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

[Erich Keane via cfe-commits]

erichkeane wrote:

Note: I discovered a bug in my 'exclusive' check that eliminated 2 items from the above list!

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