Assert tests on the first failure. (#4952)

* Assert tests on the first failure. Disable pop-up message box on assertion.

* Fix format and code style

* Move MSVC dependent code to ifdef

tests/test_assert.h

@@ -17,6 +17,9 @@
 
 extern int testing_fails;
 
+// Prepare test engine (MSVC assertion setup, etc)
+void InitTestEngine();
+
 void TestFail(const char *expval, const char *val, const char *exp,
               const char *file, int line, const char *func = 0);