vici: Make threads handling requests get canceled explicitly

Threads initiating SAs can get stuck on the semaphore in
wait_for_listener() during shutdown if the corresponding job is never
executed.  A particular case when this can happen is if more initiations
are triggered than worker threads are available.  This causes a (known)
deadlock as no workers are free anymore to process jobs (for inbound
messages or timeouts etc.), including the one to initiate an SA.
This change at least allows a proper shutdown.

src/libcharon/plugins/vici/vici_socket.c

@@ -563,8 +563,8 @@ CALLBACK(on_read, bool,
 					.id = entry->id,
 				);
 				lib->processor->queue_job(lib->processor,
-							(job_t*)callback_job_create(process_queue,
-														sel, free, NULL));
+							(job_t*)callback_job_create(process_queue, sel,
+											free, callback_job_cancel_thread));
 				entry->has_processor = TRUE;
 			}
 		}