[clang] [clang][CodeGen][SPIR-V][AMDGPU] Tweak AMDGCNSPIRV ABI to allow for the correct handling of aggregates passed to kernels / functions. (PR #102776)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> but empirically robust and guaranteed to work as the AMDGPU BE retains handling of direct passing for legacy reasons.

I would like to get rid of that someday...

https://github.com/llvm/llvm-project/pull/102776