Remove unused I/O feature

Author: alexcrichton

src/lib.rs

@@ -23,7 +23,6 @@
 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
        html_favicon_url = "http://www.rust-lang.org/favicon.ico",
        html_root_url = "http://doc.rust-lang.org/glob/")]
-#![cfg_attr(test, feature(io))]
 #![cfg_attr(all(test, windows), feature(std_misc))]
 
 use std::ascii::AsciiExt;