Make stableptr003 give more useful output

testsuite/tests/ghc-regress/lib/should_run/stableptr003.hs

 module Main where
 
+import Control.Monad
 import System.Mem.StableName
 
 main = do
   stable_list1 <- mapM makeStableName list
   stable_list2 <- mapM makeStableName list
-  print (stable_list1 == stable_list2)
+  unless (stable_list1 == stable_list2) $ do
+    let l1 = map hashStableName stable_list1
+    let l2 = map hashStableName stable_list2
+    print $ zip l1 l2
 
 list = [1..10000] :: [Integer]

testsuite/tests/ghc-regress/lib/should_run/stableptr003.stdout

-True