Don't allow non-ANSI ports for class constructors

Class constructors don't allow for non-ANSI ports. E.g. the following is
not valid.

```
class C;
  function new();
    input int i;
  endfunction
endclass
```

The parser will currently accept this, but otherwise ignore the non-ANSI
port. Modify the parser rules so that this is a syntax error.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

parse.y

@@ -892,7 +892,7 @@ class_item /* IEEE1800-2005: A.1.8 */
 	current_function = pform_push_constructor_scope(@3);
       }
     '(' tf_port_list_opt ')' ';'
-    tf_item_list_opt
+    block_item_decls_opt
     statement_or_null_list_opt
     K_endfunction endnew_opt
       { current_function->set_ports($6);