[clang] [HIP] Add warning for -mwavefrontsize64 on gfx10+ architectures (PR #140185)

[Yaxun Liu via cfe-commits]

yxsamliu wrote:

I removed the new option and changed the error into a warning.

Clang will only emit a warning about wave64 for gfx10+.

I will ask HIP runtime to add an option -Werror=unsupported-wave64 in cmake config files since HIP runtime does not support wave64 on gfx10+.

https://github.com/llvm/llvm-project/pull/140185