Add the first use of the rust benchmark tests.

src/lib.rs

@@ -2,8 +2,11 @@
 #![feature(trait_alias)]
 #![feature(path_file_prefix)]
 #![feature(is_sorted)]
+#![feature(test)]
 // TODO: #![warn(missing_docs)]
 
+extern crate test;
+
 #[cfg(feature = "compare")]
 pub mod compare;