[llvm] [VPlan] Change parent of VPReductionRecipe to VPRecipeWithIRFlags. NFC (PR #130881)

[Luke Lau via llvm-commits]

================
@@ -2369,8 +2372,7 @@ void VPReductionEVLRecipe::print(raw_ostream &O, const Twine &Indent,
   O << " = ";
   getChainOp()->printAsOperand(O, SlotTracker);
   O << " +";
-  if (isa<FPMathOperator>(getUnderlyingInstr()))
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lukel97 wrote:

That makes sense. I think @ElvisWang123 had already done something similar in a previous version of this PR like

```c++
     if (isa<FPMathOperator>(I))
       setFastMathFlags(R.getFastMathFlags());
```

in the constructor. Should that be done as a part of this PR or in a follow up?

https://github.com/llvm/llvm-project/pull/130881