Can't call event_del() without event_set() first - so call event_set()

when setting up the client.

client.c

@@ -93,6 +93,7 @@ server_started:
 	if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
 		fatal("fcntl failed");
 	imsg_init(&client_ibuf, fd);
+	event_set(&client_event, fd, EV_READ, client_callback, NULL);
 
 	if (cmdflags & CMD_SENDENVIRON)
 		client_send_environ();