[llvm] [ConstraintElim] Add tests for llvm.abs (PR #76374)

[Florian Hahn via llvm-commits]

fhahn wrote:

Thanks for putting up the tests as separate PR! Could you also add tests with predicates other than `sge` (including some that cannot be simplified) and some unsigned ones as well?

https://github.com/llvm/llvm-project/pull/76374