rm unused imports

Author: bluss

src/arraytraits.rs

@@ -5,8 +5,6 @@
 // <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.
-#[cfg(feature = "rustc-serialize")]
-use serialize::{Encodable, Encoder, Decodable, Decoder};
 
 use std::hash;
 use std::iter::FromIterator;