[llvm] [clang] [Instcombine] use zext's nneg flag for icmp folding (PR #70845)

[Léonard Oest O'Leary via llvm-commits]

leo-ard wrote:

Thanks for taking the time to review the PR. I just added another test in PhaseOrdering to make sure that the min/max intrinsics are generated

https://github.com/llvm/llvm-project/pull/70845