repair t_client.sh test after build system revolution

repair t_client.sh test after build system revolution

- run t_client.sh at "make check" time
- in t_client.sh, read t_client.rc from source *or* build dir (as before)
- @IP@ evaluates to "" now (not "ip") if iproute2 not found - adapt script
- introduce $SETUP_TIME_WAIT to delay "waiting for openvpn startup" longer
  than the default delay of 10 seconds - this is needed for test servers
  with a high network RTT

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: David Sommerseth <davids@redhat.com>
Message-Id: 20120527202737.GV1161@greenie.muc.de
URL: http://article.gmane.org/gmane.network.openvpn.devel/6616
Signed-off-by: David Sommerseth <davids@redhat.com>