remove some unneeded 'extern crate'

src/bin/cargo-miri.rs

@@ -1,7 +1,5 @@
 #![feature(inner_deref)]
 
-extern crate cargo_metadata;
-
 use std::fs::{self, File};
 use std::io::{self, Write, BufRead};
 use std::path::{PathBuf, Path};

test-cargo-miri/src/main.rs

@@ -1,7 +1,3 @@
-extern crate byteorder;
-#[cfg(test)]
-extern crate rand;
-
 use byteorder::{BigEndian, ByteOrder};
 
 fn main() {