librustc: Stop reexporting the standard modules from prelude.

src/libstd/iterator.rs

@@ -17,8 +17,11 @@ implementing the `Iterator` trait.
 
 */
 
-use prelude::*;
+use cmp;
+use iter;
 use num::{Zero, One};
+use num;
+use prelude::*;
 
 pub trait Iterator<A> {
     /// Advance the iterator and return the next value. Return `None` when the end is reached.
@@ -506,6 +509,9 @@ mod tests {
     use super::*;
     use prelude::*;
 
+    use iter;
+    use uint;
+
     #[test]
     fn test_counter_to_vec() {
         let mut it = Counter::new(0, 5).take(10);