- We don't use pga[i].pg->index, so don't overwrite it, since that seems pretty

- We don't use pga[i].pg->index, so don't overwrite it, since that seems pretty
  dangerous
- obd_dev's definition is already in a common header file, it doesn't need to be
  in each module
- add an assertion that will perhaps catch the callback bug
- fix PTL_RPC_MSG_ERR reporting, which I don't think has ever worked properly