Wrong "Perhaps you need to add" hints

Summary

cabal 3.5 and GHC 9.0.1 (I bet HEAD as well).

"Perhaps you need to add" hint is wrong in two ways: asks to add a dep that is already there or to add a dep that does not fix the compilation. This is in context of internal libraries.

Steps to reproduce

Detailed steps here:

https://github.com/haskell/cabal/issues/5782#issuecomment-820987923