[llvm] VPlan: thread plan to VPBuilder (NFC) (PR #125364)

[Florian Hahn via llvm-commits]

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@@ -83,13 +88,6 @@ class VPBuilder {
   VPBasicBlock *getInsertBlock() const { return BB; }
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fhahn wrote:

as in `getInsertBlock()->getParent()->getPlan()`

https://github.com/llvm/llvm-project/pull/125364