[llvm] [ValueTracking] Add support for `sub` in `isKnownNonEqual` (PR #87704)

[Nikita Popov via llvm-commits]

nikic wrote:

Looks like there is essentially no impact, and the impact there is does not look positive (? not entirely sure on that). As such, I don't think we should add this.

https://github.com/llvm/llvm-project/pull/87704