[llvm] [VPlan] Consolidate (ActiveLaneMask|Widen)PHI recipes (NFC) (PR #169481)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

I'm not sure if VPWidenPHIRecipe should become a header phi, I think we currently emit VPWidenPHIRecipes outside the header in the outer loop vectorization path, and it would probably be good to keep the flexibility to have it position-independet

https://github.com/llvm/llvm-project/pull/169481