add haxl patch

patches/haxl-2.3.0.0.patch

+diff --git a/Haxl/Core/DataCache.hs b/Haxl/Core/DataCache.hs
+index ed264aa..ccf0617 100644
+--- a/Haxl/Core/DataCache.hs
++++ b/Haxl/Core/DataCache.hs
+@@ -51,7 +51,7 @@ newtype DataCache res = DataCache (HashTable TypeRep (SubCache res))
+ --
+ data SubCache res =
+   forall req a . (Hashable (req a), Eq (req a), Typeable (req a)) =>
+-       SubCache (req a -> String) (a -> String) ! (HashTable (req a) (res a))
++       SubCache (req a -> String) (a -> String) !(HashTable (req a) (res a))
+        -- NB. the inner HashMap is strict, to avoid building up
+        -- a chain of thunks during repeated insertions.
+ 
+diff --git a/Haxl/Core/Fetch.hs b/Haxl/Core/Fetch.hs
+index 80bab4b..539635c 100644
+--- a/Haxl/Core/Fetch.hs
++++ b/Haxl/Core/Fetch.hs
+@@ -40,7 +40,7 @@ import Data.Either
+ import Data.Hashable
+ import Data.IORef
+ import Data.Int
+-import Data.List
++import Data.List (intercalate)
+ #if __GLASGOW_HASKELL__ < 804
+ import Data.Monoid
+ #endif