[llvm] [InstCombine] Fold operation into select, when one operand is zext of select's condition (PR #166816)

[Gábor Spaits via llvm-commits]

https://github.com/spaits approved this pull request.

LGTM. I just have a few qestions/recommendations. 

https://github.com/llvm/llvm-project/pull/166816