[llvm] [CodeGen] Avoid sinking vector comparisons during CodeGenPrepare (PR #113158)

[via llvm-commits]

goldsteinn wrote:

> Alternatively, I could also introduce a TLI hook to query the
> target if this is a preferred solution?

This seems pretty similiar to existing `shouldNormalizeToSelectSequence` or `hasMultipleConditionRegisters`.
Maybe `shouldNormalizeToSelectSequence` should become `shouldSinkComparisons` more generally (whether it be into selects or BBs).

https://github.com/llvm/llvm-project/pull/113158