[clang] [clang] Avoid memcopy for small structure with padding under -ftrivial-auto-var-init (PR #71677)

[Felipe de Azevedo Piovezan via cfe-commits]

felipepiovezan wrote:

If this gets reverted for some reason, please note that I had to update a cross-project-tests test:
https://github.com/llvm/llvm-project/pull/73566

https://github.com/llvm/llvm-project/pull/71677