[clang] [Clang][HIP] Warn when __AMDGCN_WAVEFRONT_SIZE is used in host code (PR #91478)

[Fabian Ritter via cfe-commits]

ritter-x2a wrote:

Closing this PR in favor of a more comprehensive treatment of the AMDGCN_WAVEFRONT_SIZE situation.

https://github.com/llvm/llvm-project/pull/91478