[llvm] [InstCombine] Fold copysign of selects from sign comparison to sign operand (PR #85627)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

It would also be easier to review this if you split the baseline tests into a separate commit, as per https://llvm.org/docs/InstCombineContributorGuide.html#precommit-tests

https://github.com/llvm/llvm-project/pull/85627