[llvm] [DAG] SimplifyDemandedBits - ICMP_SLT(X, 0) - only sign mask of X is required (PR #164946)

[Anikesh Parashar via llvm-commits]

an1k3sh wrote:

@topperc @RKSimon, would you mind taking another look when you get the chance?

https://github.com/llvm/llvm-project/pull/164946