[llvm] [LV][VPlan] Change the inheritance of class VPWidenSelectRecipe to class VPRecipeWithIRFlags, which allows recipe of the select to pass the fastmath flags (PR #121023)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Could you add a test case with a select with fast-math flags?

https://github.com/llvm/llvm-project/pull/121023