Few udns fixes:
Few udns fixes:

- There was test code to hardwire localhost as dns server.  Remove.
- udns_io_cb expected EV_PERSIST, event_set did not do it.  Fix.
- logging cleanup

jaiminpan/pgbouncer,digoal/pgbouncer-x2,jaiminpan/pgbouncer,digoal/pgbouncer-x2,wurenny/pgbouncer-x2,kvap/pgbouncer,dbaxa/pgbouncer,dbaxa/pgbouncer,digoal/pgbouncer-x2,jaiminpan/pgbouncer,kvap/pgbouncer,dbaxa/pgbouncer,wurenny/pgbouncer-x2,wurenny/pgbouncer-x2,jaiminpan/pgbouncer,kvap/pgbouncer,dbaxa/pgbouncer,kvap/pgbouncer,wurenny/pgbouncer-x2,digoal/pgbouncer-x2