[llvm] [DAG] Refactor X86 combineVSelectWithAllOnesOrZeros fold into a generic DAG Combine (PR #145298)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

@woruyu please can you merge against trunk? I've cleaned up the systemz and mips tests to try to reduce the codegen diff

https://github.com/llvm/llvm-project/pull/145298