[clang] [llvm] [AMDGPU] Introduce asyncmark/wait intrinsics (PR #173259)

[Krzysztof Drewniak via cfe-commits]

https://github.com/krzysz00 commented:

This is quite nice and I think will be helpful going forward.

@Hardcode84 @qedawkins @antiagainst @lialan @kuhar @bjacob as the MLIR-level folks who may be interested in using this and so are getting tagged (mostly as "hey, check out the cool new thing" with a side of "please say something now if you see any glaring red flags with this API")

https://github.com/llvm/llvm-project/pull/173259