[llvm] [InstCombine] fold `cond ? x : -x == 0` into `x == 0` (PR #85673)

[Nikita Popov via llvm-commits]

nikic wrote:

@SahilPatidar I think @arsenm meant rebase, not resolve :) There is a merge conflict.

https://github.com/llvm/llvm-project/pull/85673