Call the generate_opqaue_stubs from final

This doesn't do anything if it is not enabled

Author: thk123

src/ansi-c/ansi_c_language.cpp

@@ -196,6 +196,8 @@ Function: ansi_c_languaget::final
 
 bool ansi_c_languaget::final(symbol_tablet &symbol_table)
 {
+  generate_opaque_method_stubs(symbol_table);
+
   if(ansi_c_entry_point(symbol_table, "main", get_message_handler()))
     return true;