[llvm] [InstCombine] Fold -X / -Y -> X / Y (PR #88422)

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AtariDreams wrote:

> Please, can you stop rebasing your pull requests all the time? You are generating notifications every time you do that, and as far as I can tell you don't actually do any changes in most cases? Or did something change in the last rebase?

Edit the commit message.

https://github.com/llvm/llvm-project/pull/88422