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

[Krzysztof Drewniak via cfe-commits]

krzysz00 wrote:

Yeah, that's my proposal for metadata that's useful to record, especially since `min == max` gives the present case

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