base: Include (<$) in all exports of Functor

Previously the haddocks for Control.Monad and Data.Functor gave
the impression that `fmap` was the only Functor method.

Fixes #16681.

libraries/base/Control/Monad.hs

@@ -18,7 +18,7 @@ module Control.Monad
     (
     -- * Functor and monad classes
 
-      Functor(fmap)
+      Functor(..)
     , Monad((>>=), (>>), return)
     , MonadFail(fail)
     , MonadPlus(mzero, mplus)

libraries/base/Data/Functor.hs

@@ -39,8 +39,7 @@
 
 module Data.Functor
     (
-      Functor(fmap),
-      (<$),
+      Functor(..),
       ($>),
       (<$>),
       (<&>),