[clang] [clang] Better bitfield access units (PR #65742)

[Lu Weining via cfe-commits]

SixWeining wrote:

> For GCC, we have `-mno-unalgined-access`. We need also add this option to clang.

`-mno-unalgined-access` has been added since clang17: https://reviews.llvm.org/D149946

https://github.com/llvm/llvm-project/pull/65742