[clang] [llvm] Delegate __builtin_setjmp SP and FP save to the backend on all targets (PR #186843)

[Sean Fertile via llvm-commits]

mandlebug wrote:

> Two comments but otherwise LGTM. Thanks for the updates.

Sorry my second comment doesn't show up and I can't add one inline in the code for some reason - the comment you added back in `PPCISelLowering.cpp` has an unintended whitespace  change that you should fix before commiting.

https://github.com/llvm/llvm-project/pull/186843