[llvm] [LV] Generate scalar VPInstruction::Not if possible. (PR #152628)

[David Sherwood via llvm-commits]

david-arm wrote:

Hmm, can you wait a day or so before landing this patch? I'm worried about the potential codegen impact of this PR and would like to see the difference in generated output for some loops.

https://github.com/llvm/llvm-project/pull/152628