message: fix(s2n-quic-platform): set don't fragment flag for IPv4 mapped IPv6 addresses
diff: @@ -163,7 +163,7 @@ impl Io {
  #[cfg(s2n_quic_platform_mtu_disc)]
  {
  use std::os::unix::io::AsRawFd;
  - if tx_addr.is_ipv4() {
  +
  // IP_PMTUDISC_PROBE setting will set the DF (Don't Fragment) flag
  // while also ignoring the Path MTU. This means packets will not
  // be fragmented, and the EMSGSIZE error will not be returned for
  @@ -175,7 +175,8 @@ impl Io {
  &libc::IP_PMTUDISC_PROBE as *const _ as _,
  core::mem::size_of_val(&libc::IP_PMTUDISC_PROBE) as _,
  ))?;
  - } else {
  +
  + if tx_addr.is_ipv6() {
  libc!(setsockopt(
  tx_socket.as_raw_fd(),
  libc::IPPROTO_IPV6,
  