Fix GHC 7.0 build

Author: Bodigrim

Codec/Compression/Zlib/Internal.hs

@@ -1,5 +1,6 @@
-{-# LANGUAGE CPP, RankNTypes, DeriveDataTypeable, DeriveGeneric, BangPatterns #-}
+{-# LANGUAGE CPP, RankNTypes, DeriveDataTypeable, BangPatterns #-}
 #if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE Trustworthy #-}
 #endif
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