[llvm] [InstCombine] Slightly optimize visitFcmp (NFC) (PR #156097)

[Nikita Popov via llvm-commits]

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

LGTM, but please do not submit further PRs of this kind. The improvement here is very debatable, and reviewing this is a waste of my time.

https://github.com/llvm/llvm-project/pull/156097