[llvm] [LV] Keep duplicate recipes in VPExpressionRecipe (PR #156976)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Hmm, this only impacts printing, right? It seems like it would be simpler to just handle the case where 1 extend is shared when picking the multiply recipe, by checking if `ExpressionRecipes[1]` is an extend or widen recipe?

```
  auto *Mul = cast<VPWidenRecipe>(IsExtended ? ExpressionRecipes[2]
                                               : ExpressionRecipes[0]);
```

https://github.com/llvm/llvm-project/pull/156976