In GHC.Real, specialise 'even' and 'odd' to Int and Integer

This was previously happening by a fluke -- they were called with those types
in GHC.Real itself -- but my recent changes to specialisation mean that auto
specialisations like these are not necessarily exported.

Losing those specialisations made a huge difference to two performance tests
   perf/should_run/MethSharing
   perf/should_run/T9339

libraries/base/GHC/Real.lhs

@@ -517,6 +517,10 @@ showSigned showPos p x
 even, odd       :: (Integral a) => a -> Bool
 even n          =  n `rem` 2 == 0
 odd             =  not . even
+{-# SPECIALISE even :: Int -> Bool #-}
+{-# SPECIALISE odd  :: Int -> Bool #-}
+{-# SPECIALISE even :: Integer -> Bool #-}
+{-# SPECIALISE odd  :: Integer -> Bool #-}
 
 -------------------------------------------------------
 -- | raise a number to a non-negative integral power