[llvm] [clang] [AMDGPU] Adding the amdgpu-num-work-groups function attribute (PR #79035)

[Krzysztof Drewniak via cfe-commits]

krzysz00 wrote:

I'm suggesting that this might be a more general design and that there might be more uses for it.

https://github.com/llvm/llvm-project/pull/79035