[clang] [Sema] Support negation/parens with __builtin_available (PR #111439)

[George Burgess IV via cfe-commits]

gburgessiv wrote:

Hey Damyan, GH suggested you as a reviewer for this. Would you be able to TAL? Happy to find someone else if not :) 

https://github.com/llvm/llvm-project/pull/111439