Add some missing Generic instances.

Cabal/Distribution/Types/GenericPackageDescription.hs

@@ -192,7 +192,7 @@ instance Text FlagName where
 --
 newtype FlagAssignment
   = FlagAssignment { getFlagAssignment :: Map.Map FlagName (Int, Bool) }
-  deriving (Binary, NFData)
+  deriving (Binary, Generic, NFData)
 
 instance Eq FlagAssignment where
   (==) (FlagAssignment m1) (FlagAssignment m2)

cabal-install/Distribution/Client/PackageHash.hs

 {-# LANGUAGE RecordWildCards, NamedFieldPuns, GeneralizedNewtypeDeriving #-}
-{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE DeriveDataTypeable, DeriveGeneric #-}
 
 -- | Functions to calculate nix-style hashes for package ids.
 --
@@ -315,7 +315,7 @@ renderPackageHashInputs PackageHashInputs{
 -- package ids.
 
 newtype HashValue = HashValue BS.ByteString
-  deriving (Eq, Show, Typeable)
+  deriving (Eq, Generic, Show, Typeable)
 
 instance Binary HashValue where
   put (HashValue digest) = put digest