MXS-1389: Add test for uses_function

The test uses a uses_function type rule to restrict access to the name and
address columns.

maxscale-system-test/fwf.cpp

@@ -33,7 +33,7 @@ int main(int argc, char *argv[])
     FILE* file;
 
     sprintf(rules_dir, "%s/fw/", test_dir);
-    int N = 12;
+    int N = 13;
     int i;
 
     for (i = 1; i < N + 1; i++)