message: Reduce unnecessary cloning
diff: @@ -271,8 +271,8 @@ impl UdpAssociation {
  fn serialize(saddr: &SocketAddr) -> [u8; 18] {
  let mut result = [0; 18];
  result[..16].copy_from_slice(&match saddr.ip() {
  - IpAddr::V4(ref ip) => ip.to_ipv6_mapped(),
  - IpAddr::V6(ref ip) => ip.clone(),
  + IpAddr::V4(ref ip) => &ip.to_ipv6_mapped(),
  + IpAddr::V6(ref ip) => ip,
  }.octets());
  result[16..].copy_from_slice(&saddr.port().to_ne_bytes());
  result
  