[llvm] [VPlan] Introduce scalar loop header in plan, remove VPLiveOut. (PR #109975)

[via llvm-commits]

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@@ -8885,20 +8881,8 @@ static void addLiveOutsForFirstOrderRecurrences(
   // Start by finding out if middle block branches to scalar preheader, which is
   // not a VPIRBasicBlock, unlike Exit block - the other possible successor of
   // middle block.
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ayalz wrote:

```suggestion
```
obsolete?

https://github.com/llvm/llvm-project/pull/109975