[llvm] [VPlan] Insert VPBlendRecipes in post order. NFC (PR #201782)

[Mel Chen via llvm-commits]

================
@@ -292,6 +301,10 @@ void VPlanTransforms::introduceMasksAndLinearize(VPlan &Plan) {
     }
   }
 
+  for (VPBlockBase *VPB : reverse(RPOT))
+    if (VPB != Header)
+      Predicator.convertPhisToBlends(cast<VPBasicBlock>(VPB));
----------------
Mel-Chen wrote:

nit:
```suggestion
  for (VPBlockBase *VPBB : reverse(RPOT))
    if (VPBB != Header)
      Predicator.convertPhisToBlends(cast<VPBasicBlock>(VPBB));
```

https://github.com/llvm/llvm-project/pull/201782