[llvm] SCEV: teach isImpliedViaOperations about samesign (PR #124270)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

I'm confused about where the regression is coming from because the output from `opt -passes='print<scalar-evolution>'` is identical (?)

https://github.com/llvm/llvm-project/pull/124270