[llvm] [InstCombine] Remove one-use requirement for add iN (sext i1 X), (sext i1 Y) --> sext (X | Y) to iN (PR #90509)

[Nikita Popov via llvm-commits]

https://github.com/nikic requested changes to this pull request.

The case with two extra uses is still untested?

https://github.com/llvm/llvm-project/pull/90509