message: sendfd only works on UNIX platforms
diff: @@ -59,7 +59,6 @@ async-trait = "0.1"
  socket2 = { version = "0.4", features = ["all"] }
  tokio = { version = "1.9.0", features = ["io-util", "macros", "net", "parking_lot", "process", "rt", "sync", "time"] }
  tokio-tfo = "0.1.4"
  -sendfd = { version = "0.4", features = ["tokio"] }
  trust-dns-resolver = { version = "0.20", optional = true }
  arc-swap = { version = "1.3", optional = true }
  @@ -74,6 +73,9 @@ shadowsocks-crypto = { version = "0.2", features = [] }
  [target.'cfg(windows)'.dependencies]
  winapi = { version = "0.3", features = ["mswsock", "winsock2", "netioapi"] }
  +[target.'cfg(unix)'.dependencies]
  +sendfd = { version = "0.4", features = ["tokio"] }
  +
  # Just for the ioctl call macro
  [target.'cfg(any(target_os = "linux", target_os = "android"))'.dependencies]
  nix = "0.23"
  