Add allow(missing_docs) for benchmarks (#111)

Addition of simple module docs is not sufficient since
`block_encryptor_bench!` creates `pub fn`.

Author: newpavlov

belt-ctr/benches/belt-ctr.rs

@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(missing_docs)]
 extern crate test;
 
 cipher::stream_cipher_bench!(

cbc/benches/aes128.rs

@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(missing_docs)]
 extern crate test;
 
 cipher::block_encryptor_bench!(

cfb-mode/benches/aes128.rs

@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(missing_docs)]
 extern crate test;
 
 cipher::block_encryptor_bench!(

cfb8/benches/aes128.rs

@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(missing_docs)]
 extern crate test;
 
 cipher::block_encryptor_bench!(

ctr/benches/aes128.rs

@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(missing_docs)]
 extern crate test;
 
 cipher::stream_cipher_bench!(

ige/benches/aes128.rs

@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(missing_docs)]
 extern crate test;
 
 cipher::block_encryptor_bench!(

ofb/benches/aes128.rs

@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(missing_docs)]
 extern crate test;
 
 cipher::stream_cipher_bench!(

pcbc/benches/aes128.rs

@@ -1,4 +1,5 @@
 #![feature(test)]
+#![allow(missing_docs)]
 extern crate test;
 
 cipher::block_encryptor_bench!(