Add test case for #7611

basically using the machinery from the test case of #2110.

testsuite/tests/simplCore/should_run/T7611.hs

+{-# LANGUAGE MagicHash #-}
+
+import GHC.Exts
+
+newtype Age = Age Int
+
+myMap f [] = []
+myMap f (x:xs) = f x : myMap f xs
+
+{-# RULES "map id2" myMap (\x -> x) = id #-}
+
+mapId = myMap id
+mapIdApp x = myMap id x
+
+mapLamId = myMap (\x -> x)
+mapLamIdApp x = myMap (\x -> x) x
+
+
+same :: a -> a -> IO ()
+same x y = case reallyUnsafePtrEquality# x y of
+    1# -> putStrLn "yes"
+    _  -> putStrLn "no"
+
+main = do
+    let l = [1,2,3]
+    same (mapId l) l
+    same (mapIdApp l) l
+    same (mapLamId l) l
+    same (mapLamIdApp l) l

testsuite/tests/simplCore/should_run/T7611.stdout

+yes
+yes
+yes
+yes

testsuite/tests/simplCore/should_run/all.T

@@ -72,3 +72,4 @@ test('T9390', normal, compile_and_run, [''])
 test('T10830', extra_run_opts('+RTS -K100k -RTS'), compile_and_run, [''])
 test('T11172', normal, compile_and_run, [''])
 test('T11731', normal, compile_and_run, ['-fspec-constr'])
+test('T7611', normal, compile_and_run, [''])