Add 7.0 output for mdofail00* tests

testsuite/tests/ghc-regress/mdo/should_fail/mdofail001.stderr-ghc-7.0

+
+mdofail001.hs:10:36:
+    No instance for (Num Char)
+      arising from the literal `3'
+    Possible fix: add an instance declaration for (Num Char)
+    In the expression: 3
+    In the first argument of `l', namely `[1, 2, 3]'
+    In the expression: l [1, 2, 3]

testsuite/tests/ghc-regress/mdo/should_fail/mdofail002.stderr-ghc-7.0

+
+mdofail002.hs:10:9:
+    Conflicting definitions for `x'
+    Bound at: mdofail002.hs:10:9
+              mdofail002.hs:11:9

testsuite/tests/ghc-regress/mdo/should_fail/mdofail003.stderr-ghc-7.0

+
+mdofail003.hs:10:9:
+    Conflicting definitions for `x'
+    Bound at: mdofail003.hs:10:9
+              mdofail003.hs:11:13

testsuite/tests/ghc-regress/mdo/should_fail/mdofail004.stderr-ghc-7.0

+
+mdofail004.hs:17:5:
+    No instance for (MonadFix X)
+      arising from a do statement
+    Possible fix: add an instance declaration for (MonadFix X)
+    In the expression: mdo { return [1, 2, ....] }
+    In an equation for `z': z = mdo { return [1, ....] }