Auto merge of #466 - fiveop:warnings, r=posborne

Get rid of a few test compilation warnings

Cleans up after 0fa7250 and 40351db.

Author: homu

test/sys/test_uio.rs

@@ -2,7 +2,7 @@ use nix::sys::uio::*;
 use nix::unistd::*;
 use rand::{thread_rng, Rng};
 use std::{cmp, iter};
-use std::fs::{OpenOptions, remove_file};
+use std::fs::{OpenOptions};
 use std::os::unix::io::AsRawFd;
 
 use tempdir::TempDir;

test/test_mount.rs

@@ -128,8 +128,6 @@ exit 23";
     }
 
     pub fn test_mount_bind() {
-        use std::env;
-
         let tempdir = TempDir::new("nix-test_mount")
                           .unwrap_or_else(|e| panic!("tempdir failed: {}", e));
         let file_name = "test";