[VPlan] Strip TODO to consolidate (ActiveLaneMask|Widen)PHI (#171392)

They cannot be consolidated, as WidenPHI is not a header PHI, while
ActtiveLaneMaskPHI is.

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -3600,8 +3600,6 @@ protected:
 
 /// A recipe for generating the active lane mask for the vector loop that is
 /// used to predicate the vector operations.
-/// TODO: It would be good to use the existing VPWidenPHIRecipe instead and
-/// remove VPActiveLaneMaskPHIRecipe.
 class VPActiveLaneMaskPHIRecipe : public VPHeaderPHIRecipe {
 public:
   VPActiveLaneMaskPHIRecipe(VPValue *StartMask, DebugLoc DL)

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -4407,8 +4407,6 @@ void VPWidenPHIRecipe::printRecipe(raw_ostream &O, const Twine &Indent,
 }
 #endif
 
-// TODO: It would be good to use the existing VPWidenPHIRecipe instead and
-// remove VPActiveLaneMaskPHIRecipe.
 void VPActiveLaneMaskPHIRecipe::execute(VPTransformState &State) {
   BasicBlock *VectorPH =
       State.CFG.VPBB2IRBB.at(getParent()->getCFGPredecessor(0));