std: Add a new `env` module

This is an implementation of [RFC 578][rfc] which adds a new `std::env` module
to replace most of the functionality in the current `std::os` module. More
details can be found in the RFC itself, but as a summary the following methods
have all been deprecated:

[rfc]: https://github.com/rust-lang/rfcs/pull/578

* `os::args_as_bytes`   => `env::args`
* `os::args`            => `env::args`
* `os::consts`          => `env::consts`
* `os::dll_filename`    => no replacement, use `env::consts` directly
* `os::page_size`       => `env::page_size`
* `os::make_absolute`   => use `env::current_dir` + `join` instead
* `os::getcwd`          => `env::current_dir`
* `os::change_dir`      => `env::set_current_dir`
* `os::homedir`         => `env::home_dir`
* `os::tmpdir`          => `env::temp_dir`
* `os::join_paths`      => `env::join_paths`
* `os::split_paths`     => `env::split_paths`
* `os::self_exe_name`   => `env::current_exe`
* `os::self_exe_path`   => use `env::current_exe` + `pop`
* `os::set_exit_status` => `env::set_exit_status`
* `os::get_exit_status` => `env::get_exit_status`
* `os::env`             => `env::vars`
* `os::env_as_bytes`    => `env::vars`
* `os::getenv`          => `env::var` or `env::var_string`
* `os::getenv_as_bytes` => `env::var`
* `os::setenv`          => `env::set_var`
* `os::unsetenv`        => `env::remove_var`

Many function signatures have also been tweaked for various purposes, but the
main changes were:

* `Vec`-returning APIs now all return iterators instead
* All APIs are now centered around `OsString` instead of `Vec<u8>` or `String`.
  There is currently on convenience API, `env::var_string`, which can be used to
  get the value of an environment variable as a unicode `String`.

All old APIs are `#[deprecated]` in-place and will remain for some time to allow
for migrations. The semantics of the APIs have been tweaked slightly with regard
to dealing with invalid unicode (panic instead of replacement).

The new `std::env` module is all contained within the `env` feature, so crates
must add the following to access the new APIs:

    #![feature(env)]

[breaking-change]

1 files changed, 2 insertions, 7 deletions

diff --git a/src/libstd/sys/windows/tcp.rs b/src/libstd/sys/windows/tcp.rs
index 64e440331c1..4804ca510cb 100644
--- a/src/libstd/sys/windows/tcp.rs
+++ b/src/libstd/sys/windows/tcp.rs
@@ -14,12 +14,11 @@ use libc;
 use mem;
 use ptr;
 use prelude::v1::*;
-use super::{last_error, last_net_error, retry, sock_t};
+use super::{last_error, last_net_error, sock_t};
 use sync::Arc;
 use sync::atomic::{AtomicBool, Ordering};
-use sys::fs::FileDesc;
 use sys::{self, c, set_nonblocking, wouldblock, timer};
-use sys_common::{self, timeout, eof, net};
+use sys_common::{timeout, eof, net};
 
 pub use sys_common::net::TcpStream;
 
@@ -202,10 +201,6 @@ impl TcpAcceptor {
         Err(eof())
     }
 
-    pub fn socket_name(&mut self) -> IoResult<ip::SocketAddr> {
-        net::sockname(self.socket(), libc::getsockname)
-    }
-
     pub fn set_timeout(&mut self, timeout: Option<u64>) {
         self.deadline = timeout.map(|a| timer::now() + a).unwrap_or(0);
     }