std: Deprecate the std::old_io::net primitives

The `std::net` primitives should be ready for use now and as a result the old
ones are now deprecated and slated for removal. Most TCP/UDP functionality is
now available through `std::net` but the `std::old_io::net::pipe` module is
removed entirely from the standard library.

Unix socket funtionality can be found in sfackler's [`unix_socket`][unix] crate
and there is currently no replacement for named pipes on Windows.

[unix]: https://crates.io/crates/unix_socket

[breaking-change]

src/libstd/sys/unix/ext.rs

@@ -73,42 +73,49 @@ impl AsRawFd for old_io::pipe::PipeStream {
     }
 }
 
+#[allow(deprecated)]
 impl AsRawFd for old_io::net::pipe::UnixStream {
     fn as_raw_fd(&self) -> Fd {
         self.as_inner().fd()
     }
 }
 
+#[allow(deprecated)]
 impl AsRawFd for old_io::net::pipe::UnixListener {
     fn as_raw_fd(&self) -> Fd {
         self.as_inner().fd()
     }
 }
 
+#[allow(deprecated)]
 impl AsRawFd for old_io::net::pipe::UnixAcceptor {
     fn as_raw_fd(&self) -> Fd {
         self.as_inner().fd()
     }
 }
 
+#[allow(deprecated)]
 impl AsRawFd for old_io::net::tcp::TcpStream {
     fn as_raw_fd(&self) -> Fd {
         self.as_inner().fd()
     }
 }
 
+#[allow(deprecated)]
 impl AsRawFd for old_io::net::tcp::TcpListener {
     fn as_raw_fd(&self) -> Fd {
         self.as_inner().fd()
     }
 }
 
+#[allow(deprecated)]
 impl AsRawFd for old_io::net::tcp::TcpAcceptor {
     fn as_raw_fd(&self) -> Fd {
         self.as_inner().fd()
     }
 }
 
+#[allow(deprecated)]
 impl AsRawFd for old_io::net::udp::UdpSocket {
     fn as_raw_fd(&self) -> Fd {
         self.as_inner().fd()

src/libstd/sys/unix/tcp.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![allow(deprecated)]
+
 use prelude::v1::*;
 
 use old_io::net::ip;