move TH instance Eq1 NValue' to the parent as derivable

Eq1 instance was previously derived as an orphan through TemplateHaskell.
And that TH instance when moved into Nix.Value was breaking the NValue' data
constructor deriving.

So it is moved as derivable instance.

Author: Anton-Latukha

src/Nix/Value.hs

@@ -176,7 +176,7 @@ type MonadDataContext f (m :: * -> *)
 -- | At the time of constructor, the expected arguments to closures are values
 --   that may contain thunks. The type of such thunks are fixed at that time.
 newtype NValue' t f m a = NValue { _nValue :: f (NValueF (NValue t f m) m a) }
-    deriving (Generic, Typeable, Functor, Foldable)
+    deriving (Generic, Typeable, Functor, Foldable, Eq1)
 
 instance (Comonad f, Show a) => Show (NValue' t f m a) where
   show (NValue (extract -> v)) = show v

src/Nix/Value/Equal.hs

@@ -30,7 +30,6 @@ import           Control.Monad.Free
 import           Control.Monad.Trans.Class
 import           Control.Monad.Trans.Except
 import           Data.Align
-import           Data.Eq.Deriving
 import           Data.Functor.Identity
 import qualified Data.HashMap.Lazy             as M
 import           Data.These
@@ -173,5 +172,3 @@ thunkEqM lt rt = force lt $ \lv -> force rt $ \rv ->
         (NVList _     , NVList _     ) -> unsafePtrEq
         (NVSet _ _    , NVSet _ _    ) -> unsafePtrEq
         _                              -> valueEqM lv rv
-
-$(deriveEq1 ''NValue')