[llvm] [X86] Fix stack temporary leaks for x87 float returns (PR #213134)

[Oliver Hunt via llvm-commits]

https://github.com/ojhunt commented:

Ok the code changes don't look overtly wrong to me, but I'd like someone from AMD or Intel to verify this.

Fun thing I encountered:
1. Forget that diffs are terrible with indentation change
2. Remember I can hide whitespace changes, making the change much clearer
3. Start complaining about comment reformatting in unrelated code
4. Realise the "unrelated" formatting changes were due to the indentation change, but because of (2) the indentation change is invisible.
5. shake fist at the contradictory fixes for whitespace changes in diffs.

:D

https://github.com/llvm/llvm-project/pull/213134