Revert "GCC ABI Compatibility: Preserve alignment of non-pod members in packed structs"

This reverts commit 27712337.

There are still some issues with this change to be worked out, so revert
this patch to avoid having to change ABIs from LLVM 13->14 and then again from
LLVM 14->15.  See discussion in https://reviews.llvm.org/D118511