[clang] [Clang][HIP] Deprecate the AMDGCN_WAVEFRONT_SIZE macros (PR #112849)

[Alex Voicu via cfe-commits]

AlexVlx wrote:

> > CI is red but it seems to be some weird Windows failures. Ideally if the builtin / intrinsic is the way to go I'd like that to be folded much earlier because it prevents loop unrolling for cases like SIMT scan / reduce.

#114481 should deal with this @arsenm @jhuber6.

https://github.com/llvm/llvm-project/pull/112849