[llvm] [AMDGPU] Add an asm directive to track code_object_version (PR #76267)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> @slinder1 @arsenm Ah, so code_object_version is only meaningful on HSA OSes? I originally chose 'amdgcn' since I thought it was also meaningful on PAL/Mesa. The update renames the directive to `amdhsa_code_object_version` and only emits/parses it on HSA triples.
> 
> I noticed that clang emits the IR module flag, `amdgpu_code_object_verison` on PAL/mesa. Should that be updated to just emit on HSA? Thanks!

It's not exactly well defined enough to make a definitive statement. The hope was mesa would follow HSA code objects, but that maintenance work never happened. Less sure about PAL

https://github.com/llvm/llvm-project/pull/76267