[llvm] [LV] Move condition to VPPartialReductionRecipe::execute (PR #166136)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Hmm, with this change IIUC we now assume that the cost of partial reduction with and without selects will be the same. Is that correct in all cases?

https://github.com/llvm/llvm-project/pull/166136