Events: fixed "port_dissociate() failed" alerts with eventport. If an attempt is made to delete an event which was already reported, port_dissociate() returns an error. Fix is avoid doing anything if ev->active is not set. Possible alternative approach would be to avoid calling ngx_del_event() at all if ev->active is not set. This approach, however, will require something else to re-add the other event of the connection, since both read and write events are dissociated if an event is reported on a file descriptor. Currently ngx_eventport_del_event() re-associates write event if called to delete read event, and vice versa.