[llvm] [VPlan] Split out VPBlendRecipe simplifications from simplifyRecipes. NFC (PR #134073)

[Luke Lau via llvm-commits]

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@@ -183,6 +183,10 @@ struct VPlanTransforms {
   /// CanonicalIVTy as type for all un-typed live-ins in VPTypeAnalysis.
   static void simplifyRecipes(VPlan &Plan, Type &CanonicalIVTy);
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lukel97 wrote:

It is but it's also called from LoopVectorizer.cpp, unlike the other passes in VPlanTransforms::optimize

https://github.com/llvm/llvm-project/pull/134073