Add extra NULL argument at the end of fail* APIs

The fail, fail_unless, and fail_if APIS were expected to contain
a message explaining the failure. This was never enforced, and
it was possible to write unit tests without providing messages.

In github.com//pull/249 a change was
introduced to add printf argument checking to the Check assert
APIS, including the fail APIs. There were a few fixes for this
in github.com/libcheck/check/releases/tag/0.15.1. Those changes
proved problematic for the uses of the fail* APIs without arguments,
as those uses were now flagged as missing the necessary arguments.

A fix proposed by heftig in github.com//issues/293
is to add a new NULL to the end of every fail* call in the macro
itself. For users of these APIs who do pass a message there will
be a new warning about too many arguments. As the fail APIs are
deprecated, this new warning is a reasonable trade-off, and can
be avoided by switching fail* calls to ck_assert* calls.

src/check.h.in

@@ -466,7 +466,10 @@ static void __testname ## _fn (int _i CK_ATTRIBUTE_UNUSED)
  *
  * This call is deprecated.
  */
-#define fail_unless ck_assert_msg
+#define fail_unless(expr, ...) \
+  (expr) ? \
+    _mark_point(__FILE__, __LINE__) : \
+    _ck_assert_failed(__FILE__, __LINE__, "Assertion '"#expr"' failed" , ## __VA_ARGS__, NULL)
 
 /*
  * Fail the test case if expr is false
@@ -480,15 +483,15 @@ static void __testname ## _fn (int _i CK_ATTRIBUTE_UNUSED)
  */
 #define fail_if(expr, ...)\
   (expr) ? \
-     _ck_assert_failed(__FILE__, __LINE__, "Failure '"#expr"' occurred" , ## __VA_ARGS__) \
+     _ck_assert_failed(__FILE__, __LINE__, "Failure '"#expr"' occurred" , ## __VA_ARGS__, NULL) \
      : _mark_point(__FILE__, __LINE__)
 
 /*
  * Fail the test
  *
  * This call is deprecated.
  */
-#define fail ck_abort_msg
+#define fail(...) _ck_assert_failed(__FILE__, __LINE__, "Failed" , ## __VA_ARGS__, NULL)
 
 /*
  * This is called whenever an assertion fails.