[llvm] [ConstraintElim] Use isKnownNonNegative for signed->unsigned transfer. (PR #72879)

[Florian Hahn via llvm-commits]

fhahn wrote:

> LGTM, thanks! (Perhaps commit description can be generalized not only to SLT now, simplifyed -> simplified).

Updated the message (I only updated the commit message, not the PR description.....)

https://github.com/llvm/llvm-project/pull/72879