[llvm] [VPlan] Add exit phi operands during initial construction (NFC). (PR #136455)

[via llvm-commits]

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@@ -9392,11 +9392,7 @@ collectUsersInExitBlocks(Loop *OrigLoop, VPRecipeBuilder &Builder,
         continue;
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ayalz wrote:

Independent: can R iterate over ExitVPBB->phis() above?

https://github.com/llvm/llvm-project/pull/136455