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

[Fabian Ritter via cfe-commits]

ritter-x2a wrote:

> > > Should we move on with the deprecation of the macros with this PR then? Please let me know if there are technical concerns remaining with the PR or approve it so that it can land in trunk.
> > 
> > 
> > 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.
> 
> Let me rebase so that CI runs again; Windows CI was a bit of a mess in the last week or so.

CI looks better now.

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