Add `{-# MINIMAL #-}` annotations to typeclasses

This makes use of the new `{-# MINIMAL #-}` facility (see #7633)
for the following typeclasses

 - `Bits`
 - `Foldable`
 - `Fractional`
 - `Num`
 - `MonadZip`
 - `Read`
 - `Show`
 - `Storable`
 - `Traversable`

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>