[llvm] [InstCombine] Fold fcmp ogt (x - y), 0 into fcmp ogt x, y #85245 (PR #85506)

[Jay Foad via llvm-commits]

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

LGTM, just a couple of stylistic nits inline.

https://github.com/llvm/llvm-project/pull/85506