Export collections::hash as std::collections::hash

Needed to make #[deriving(Hash)] work within libstd itself.

Author: Keegan McAllister

src/libstd/collections/mod.rs

@@ -19,7 +19,7 @@ pub use core_collections::{Set, MutableSet, Deque, MutableSeq};
 pub use core_collections::{Bitv, BitvSet, BTree, DList, EnumSet};
 pub use core_collections::{PriorityQueue, RingBuf, SmallIntMap};
 pub use core_collections::{TreeMap, TreeSet, TrieMap, TrieSet};
-pub use core_collections::{bitv, btree, dlist, enum_set};
+pub use core_collections::{bitv, btree, dlist, enum_set, hash};
 pub use core_collections::{priority_queue, ringbuf, smallintmap, treemap, trie};
 
 pub use self::hashmap::{HashMap, HashSet};