[clang] [CIR][AMDGPU] Add support for AMDGCN s_sendmsg_rtn builtins (PR #223226)

[Ayokunle Amodu via cfe-commits]

ayokunle321 wrote:

> I'm personally not a big fan of the fact that we feel the need to have a run for each amdgpu11.X, but it follows the existing pattern and changing it would be out-of-scope, so let's roll with it for now.

Could add a TODO comment?

https://github.com/llvm/llvm-project/pull/223226