community/libffi3.3-compat: remove

This package was introduced to make ghc compile again. With e13c29bf (community/ghc: use embedded libffi, llvm12, drop gold, 2021-10-11), ghc uses an embedded libffi to help transition to a new ffi version, so this package is no longer required.

This also rebuilds ghc to use system libffi again and rebuilds depend packages against it.

Cabal is still an issue though. It cannot be built with ghc9 yet. As a result, the packages that require cabal cannot be enabled yet, and because libffi.so.7 is missing, they can no longer be executed.