Removed prelude::* from libstd files.

This replaces the imports from the prelude with the re-exported symbols.

src/libstd/reference.rs

@@ -11,7 +11,7 @@
 //! Utilities for references
 
 #[cfg(not(test))]
-use prelude::*;
+use cmp::{Eq,Ord,Ordering,TotalEq,TotalOrd};
 
 // Equality for region pointers
 #[cfg(not(test))]