deque: separate the methods that need Copy

src/libstd/deque.rs

@@ -37,12 +37,14 @@ impl<T> Mutable for Deque<T> {
     }
 }
 
-impl<T: Copy> Deque<T> {
+impl<T> Deque<T> {
     static pure fn new() -> Deque<T> {
         Deque{nelts: 0, lo: 0, hi: 0,
               elts: vec::from_fn(initial_capacity, |_| None)}
     }
+}
 
+impl<T: Copy> Deque<T> {
     fn add_front(&mut self, t: T) {
         let oldlo: uint = self.lo;
         if self.lo == 0u {