[clang] [Clang][AMDGPU] Add builtins for instrinsic `llvm.amdgcn.raw.buffer.store` (PR #94576)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> "aggregates" here might even be unusual cases like `<4 x i8>`

Vectors aren't aggregates and are more reasonable 

https://github.com/llvm/llvm-project/pull/94576