[clang] [Clang][HIP] Warn when __AMDGCN_WAVEFRONT_SIZE is used in host code without relying on target-dependent overload resolution (PR #109663)

[Artem Belevich via cfe-commits]

Artem-B wrote:

@ritter-x2a That's an outline of a strawman plan in case one does nave nontrivial amount of existing code that depends on this macro, and assuming that we still want to have a host-side macro for the wavefront size. If the end goal is not to have the host-side macro at all, then we don't need to complicate things that much. Just start deprecate, and remove it on the host.

https://github.com/llvm/llvm-project/pull/109663