split out module to work around badly named symbol in directory-1.2.6.2

Sadly my bug report about this is not going to get fixed it seems, so
I have to drag around a whole added module file just to deal with it.

https://github.com/haskell/directory/issues/52

Utility/Directory.hs

@@ -6,15 +6,14 @@
  -}
 
 {-# LANGUAGE CPP #-}
-{-# OPTIONS_GHC -fno-warn-tabs -w #-}
+{-# OPTIONS_GHC -fno-warn-tabs #-}
 
 module Utility.Directory (
 	module Utility.Directory,
-	module System.Directory
+	module Utility.SystemDirectory
 ) where
 
 import System.IO.Error
-import System.Directory hiding (isSymbolicLink)
 import Control.Monad
 import System.FilePath
 import Control.Applicative
@@ -31,6 +30,7 @@ import Utility.SafeCommand
 import Control.Monad.IfElse
 #endif
 
+import Utility.SystemDirectory
 import Utility.PosixFiles
 import Utility.Tmp
 import Utility.Exception

Utility/SystemDirectory.hs

@@ -0,0 +1,16 @@
+{- System.Directory without its conflicting isSymbolicLink
+ -
+ - Copyright 2016 Joey Hess <id@joeyh.name>
+ -
+ - License: BSD-2-clause
+ -}
+
+-- Disable warnings because only some versions of System.Directory export
+-- isSymbolicLink.
+{-# OPTIONS_GHC -fno-warn-tabs -w #-}
+
+module Utility.SystemDirectory (
+	module System.Directory
+) where
+
+import System.Directory hiding (isSymbolicLink)