Fix build with QuickCheck 2.8.2

It added some instances I had also implemented.

Utility/QuickCheck.hs

@@ -6,7 +6,7 @@
  -}
 
 {-# OPTIONS_GHC -fno-warn-orphans #-}
-{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE TypeSynonymInstances, CPP #-}
 
 module Utility.QuickCheck
 	( module X
@@ -21,11 +21,13 @@ import qualified Data.Set as S
 import Control.Applicative
 import Prelude
 
+#if ! MIN_VERSION_QuickCheck(2,8,2)
 instance (Arbitrary k, Arbitrary v, Eq k, Ord k) => Arbitrary (M.Map k v) where
 	arbitrary = M.fromList <$> arbitrary
 
 instance (Arbitrary v, Eq v, Ord v) => Arbitrary (S.Set v) where
 	arbitrary = S.fromList <$> arbitrary
+#endif
 
 {- Times before the epoch are excluded. -}
 instance Arbitrary POSIXTime where

debian/changelog

@@ -15,6 +15,7 @@ git-annex (6.20160115) UNRELEASED; urgency=medium
     effect.
   * assistant: Use udisks2 dbus events to detect when disks are mounted,
     instead of relying on gnome/kde stuff that is not stable.
+  * Fix build with QuickCheck 2.8.2
 
  -- Joey Hess <id@joeyh.name>  Fri, 15 Jan 2016 14:05:01 -0400
 

doc/bugs/Doesn__39__t_build_with_QuickCheck_2.8.2.mdwn

@@ -28,3 +28,6 @@ git-annex 6.20160114, on Arch Linux x86_64.
 
 ### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
 Yes, it built fine with QuickCheck 2.8. I didn't test with 2.8.1, though.
+
+> ifdefed those instances out with this version of quickcheck. [[done]]
+> --[[Joey]]