Fix console infinite loop

When the client console exits, the mainloop goes in an infinite loop
as the handler is not removed and we are notified from the disconnection
indefinitely.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

src/lxc/console.c

@@ -237,6 +237,13 @@ static int console_handler(int fd, void *data, struct lxc_epoll_descr *descr)
 		return 1;
 	}
 
+	if (!r) {
+		INFO("console client has exited");
+		lxc_mainloop_del_handler(descr, fd);
+		close(fd);
+		return 0;
+	}
+
 	/* no output for the console, do nothing */
 	if (console->peer == -1)
 		return 0;