lan_discovery_WOL: lan discovery almost done

Signed-off-by: fufesou <shuanglongchen@yeah.net>

libs/hbb_common/src/udp.rs

@@ -37,6 +37,7 @@ fn new_socket(addr: SocketAddr, reuse: bool, buf_size: usize) -> Result<Socket,
         addr,
         socket.recv_buffer_size()
     );
+    socket.set_nonblocking(true)?;
     socket.bind(&addr.into())?;
     Ok(socket)
 }