Fix obvious memory leaks in the std_vector example

Delete the class when we're done with it.

Examples/c/std_vector/runme.c

@@ -35,5 +35,7 @@ int main() {
     printf("%s %d\n", A_name_get(a), A_value_get(a));
   }
   
+  delete_Klass(klass);
+
   SWIG_exit(0);
 }