gracefully handle 7.10 modules if present

src/Base.hs

@@ -45,7 +45,9 @@ import GHC.Types as X (
   , Word
   , Ordering
   , IO
+#if ( __GLASGOW_HASKELL__ >= 710 )
   , Coercible
+#endif
   )
 
 infixr 0 $!

src/Protolude.hs

@@ -128,10 +128,19 @@ import Data.Set as X (Set)
 import Data.Sequence as X (Seq)
 import Data.IntMap as X (IntMap)
 import Data.IntSet as X (IntSet)
+
+#if ( __GLASGOW_HASKELL__ >= 710 )
 import Data.Proxy as X (
     Proxy(..)
   )
 
+import Data.Void as X (
+    Void
+  , absurd
+  , vacuous
+  )
+#endif
+
 -- Monad transformers
 import Control.Monad.State as X (
     MonadState