Auto merge of #21543 - alexcrichton:old-io, r=aturon

In preparation for the I/O rejuvination of the standard library, this commit
renames the current `io` module to `old_io` in order to make room for the new
I/O modules. It is expected that the I/O RFCs will land incrementally over time
instead of all at once, and this provides a fresh clean path for new modules to
enter into as well as guaranteeing that all old infrastructure will remain in
place for some time.

As each `old_io` module is replaced it will be deprecated in-place for new
structures in `std::{io, fs, net}` (as appropriate).

This commit does *not* leave a reexport of `old_io as io` as the deprecation
lint does not currently warn on this form of use. This is quite a large breaking
change for all imports in existing code, but all functionality is retained
precisely as-is and path statements simply need to be renamed from `io` to
`old_io`.

[breaking-change]

3 files changed, 3 insertions, 3 deletions

diff --git a/src/libstd/path/mod.rs b/src/libstd/path/mod.rs
index 06d930ce50a..1b09fb92737 100644
--- a/src/libstd/path/mod.rs
+++ b/src/libstd/path/mod.rs
@@ -49,7 +49,7 @@
 //! ## Example
 //!
 //! ```rust
-//! use std::io::fs::PathExtensions;
+//! use std::old_io::fs::PathExtensions;
 //!
 //! let mut path = Path::new("/tmp/path");
 //! println!("path: {}", path.display());
diff --git a/src/libstd/path/posix.rs b/src/libstd/path/posix.rs
index 100876271b3..202d81f5696 100644
--- a/src/libstd/path/posix.rs
+++ b/src/libstd/path/posix.rs
@@ -14,7 +14,7 @@ use clone::Clone;
 use cmp::{Ordering, Eq, Ord, PartialEq, PartialOrd};
 use fmt;
 use hash;
-use io::Writer;
+use old_io::Writer;
 use iter::{AdditiveIterator, Extend};
 use iter::{Iterator, IteratorExt, Map};
 use marker::Sized;
diff --git a/src/libstd/path/windows.rs b/src/libstd/path/windows.rs
index bd5f8416577..9f5ed177918 100644
--- a/src/libstd/path/windows.rs
+++ b/src/libstd/path/windows.rs
@@ -20,7 +20,7 @@ use clone::Clone;
 use cmp::{Ordering, Eq, Ord, PartialEq, PartialOrd};
 use fmt;
 use hash;
-use io::Writer;
+use old_io::Writer;
 use iter::{AdditiveIterator, Extend};
 use iter::{Iterator, IteratorExt, Map, repeat};
 use mem;