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

[via cfe-commits]

serge-sans-paille wrote:

@omjavaid thanks for the revert. Life was in the way today and I couldn't handle that properly. The patch was trivial, I'm going to recommit soon.

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