T229: Fix name of WORD_SIZE macro

tests/T229.hs

 {-# LANGUAGE CPP #-}
 
+#include "MachDeps.h"
+
 import Data.Array.MArray
 import Data.Array.IO
 import Data.Word
@@ -7,7 +9,7 @@ import Data.Word
 main :: IO ()
 main = do
   -- This should fail due to integer overflow
-#if WORD_SIZE == 8
+#if WORD_SIZE_IN_BITS == 64
   m <- newArray_ (0,2^62-1) :: IO (IOUArray Int Word32) -- allocates 0 bytes
   readArray m 17 >>= print -- Read some random location in address space
 #else