Fix: call circuit_has_opened() for rendezvous circuit
In circuit_get_open_circ_or_launch(), for a rendezvous circuit,
rend_client_rendcirc_has_opened() but circuit_has_opened() is preferred here
since it will call the right function for a specific circuit purpose.
Furthermore, a controller event is triggered where the former did not.
Signed-off-by: David Goulet <dgoulet@ev0ke.net>