Fix warnings

src/nproc/nproc.rs

@@ -67,7 +67,7 @@ pub fn uumain(args: Vec<String>) -> isize {
         ignore += match os::getenv("OMP_NUM_THREADS") {
             Some(threadstr) => match threadstr.parse() {
                 Ok(num) => num,
-                Err(e)=> 0
+                Err(_)=> 0
             },
             None => 0
         };

src/sort/sort.rs

@@ -146,7 +146,7 @@ fn frac_compare(a: &String, b: &String) -> Ordering {
 }
 
 #[inline(always)]
-fn print_sorted<S, T: Iterator<Item=S>>(mut iter: T) where S: std::fmt::Display {
+fn print_sorted<S, T: Iterator<Item=S>>(iter: T) where S: std::fmt::Display {
     for line in iter {
         print!("{}", line);
     }

src/tail/tail.rs

@@ -242,7 +242,7 @@ macro_rules! tail_impl (
         // count lines/chars. When reaching the end of file, output the data in the
         // ringbuf.
         let mut ringbuf: RingBuf<$kind> = RingBuf::new();
-        let mut data = $reader.$kindfn().skip(
+        let data = $reader.$kindfn().skip(
             if $beginning {
                 let temp = $count;
                 $count = ::std::usize::MAX;