auto merge of #10457 : alexcrichton/rust/native-io, r=brson

This commit re-organizes the io::native module slightly in order to have a
working implementation of rtio::IoFactory which uses native implementations. The
goal is to seamlessly multiplex among libuv/native implementations wherever
necessary.

Right now most of the native I/O is unimplemented, but we have existing bindings
for file descriptors and processes which have been hooked up. What this means is
that you can now invoke println!() from libstd with no local task, no local
scheduler, and even without libuv.

There's still plenty of work to do on the native I/O factory, but this is the
first steps into making it an official portion of the standard library. I don't
expect anyone to reach into io::native directly, but rather only std::io
primitives will be used. Each std::io interface seamlessly falls back onto the
native I/O implementation if the local scheduler doesn't have a libuv one
(hurray trait ojects!)

src/test/bench/shootout-k-nucleotide-pipes.rs

@@ -154,7 +154,7 @@ fn make_sequence_processor(sz: uint,
 // given a FASTA file on stdin, process sequence THREE
 fn main() {
     use std::io::Reader;
-    use std::io::native::stdio;
+    use std::io::stdio;
     use std::io::mem::MemReader;
     use std::io::buffered::BufferedReader;
 

src/test/run-pass/native-print-no-runtime.rs

@@ -0,0 +1,19 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// xfail-fast
+
+#[no_uv];
+
+#[start]
+fn main(_: int, _: **u8) -> int {
+    println!("hello");
+    0
+}

src/test/run-pass/native-print-no-uv.rs

@@ -0,0 +1,17 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// xfail-fast
+
+#[no_uv];
+
+fn main() {
+    println!("hello");
+}