Use base-compat for our custom prelude.

This should give us more complete coverage of newer
base features.

See #4255.

pandoc.cabal

@@ -626,7 +626,8 @@ test-suite test-pandoc
                   containers >= 0.4.2.1 && < 0.6,
                   executable-path >= 0.0 && < 0.1,
                   zip-archive >= 0.2.3.4 && < 0.4,
-                  xml >= 1.3.12 && < 1.4
+                  xml >= 1.3.12 && < 1.4,
+                  base-compat >= 0.9
   if flag(old-locale)
      build-depends: old-locale >= 1 && < 1.1,
                     time >= 1.2 && < 1.5

prelude/Prelude.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE PackageImports #-}
 {-# LANGUAGE CPP #-}
 
@@ -6,21 +7,10 @@
 
 module Prelude
 (
-  module P
-#if MIN_VERSION_base(4,8,0)
-#else
-, Monoid(..)
-, Applicative(..)
-, (<$>)
-, (<$)
-#endif
+  module Prelude.Compat
+, module Monoid.Compat
 )
 where
 
-#if MIN_VERSION_base(4,8,0)
-import "base" Prelude as P
-#else
-import "base" Prelude as P
-import Control.Applicative
-import Data.Monoid
-#endif
+import Prelude.Compat
+import Monoid.Compat