[clang] [clang] Strict aliasing warning ala GCC [PR50066] (PR #74155)

[Nathan Sidwell via cfe-commits]

urnathan wrote:

> Thank you for your efforts! I scratched the surface a bit; not qualified to do an in-depth review. Can you also add a release note?

Thanks for your comments.  A release note is added.

https://github.com/llvm/llvm-project/pull/74155