- there is something wrong in the new buildsys: If one selects ip and has e..g...

- there is something wrong in the new buildsys: If one selects ip and has e..g rule or route unset, ip still wants to build those.
  This fails (correctly) since rtnl_rttable_n2a and rtnl_rtrealm_n2a aren't available if they were turned off. TODO: Talk to vda about this