[clang] [llvm] [LLVM] Fix incorrect alignment on AMDGPU variadics (PR #96370)

[Jon Chesterfield via cfe-commits]

https://github.com/JonChesterfield requested changes to this pull request.

Patch should not land. Need to know what bug this was trying to address to guess at what the right fix would be.

https://github.com/llvm/llvm-project/pull/96370