[llvm] IVDescriptors: cut wasteful FAnyOf checking (NFC) (PR #118393)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

This effectively makes FAnyOf dead, right? In that case it should be removed and `IAnyOf` -> `AnyOf`?

https://github.com/llvm/llvm-project/pull/118393