[clang] Handle constant "pointers" for `__atomic_always_lock_free`/`__atomic_is_lock_free`. (PR #99340)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

Thanks for this! It should probably have a release note + documentation so users know this is a supported behavior?

https://github.com/llvm/llvm-project/pull/99340