std: Stabilize the `hash` module

This commit is an implementation of [RFC 823][rfc] which is another pass over
the `std::hash` module for stabilization. The contents of the module were not
entirely marked stable, but some portions which remained quite similar to the
previous incarnation are now marked `#[stable]`. Specifically:

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0823-hash-simplification.md

* `std::hash` is now stable (the name)
* `Hash` is now stable
* `Hash::hash` is now stable
* `Hasher` is now stable
* `SipHasher` is now stable
* `SipHasher::new` and `new_with_keys` are now stable
* `Hasher for SipHasher` is now stable
* Many `Hash` implementations are now stable

All other portions of the `hash` module remain `#[unstable]` as they are less
commonly used and were recently redesigned.

This commit is a breaking change due to the modifications to the `std::hash` API
and more details can be found on the [RFC][rfc].

Closes #22467
[breaking-change]

2 files changed, 2 insertions, 3 deletions

diff --git a/src/libtest/lib.rs b/src/libtest/lib.rs
index 2cb30ad9804..a03048e39b9 100644
--- a/src/libtest/lib.rs
+++ b/src/libtest/lib.rs
@@ -37,7 +37,6 @@
 #![feature(collections)]
 #![feature(core)]
 #![feature(env)]
-#![feature(hash)]
 #![feature(int_uint)]
 #![feature(old_io)]
 #![feature(old_path)]
diff --git a/src/libtest/stats.rs b/src/libtest/stats.rs
index 04617757465..e7b5820006b 100644
--- a/src/libtest/stats.rs
+++ b/src/libtest/stats.rs
@@ -12,7 +12,7 @@
 
 use std::cmp::Ordering::{self, Less, Greater, Equal};
 use std::collections::hash_map::Entry::{Occupied, Vacant};
-use std::collections::hash_map::{self, Hasher};
+use std::collections::hash_map;
 use std::hash::Hash;
 use std::mem;
 use std::num::{Float, FromPrimitive};
@@ -333,7 +333,7 @@ pub fn winsorize<T: Float + FromPrimitive>(samples: &mut [T], pct: T) {
 /// Returns a HashMap with the number of occurrences of every element in the
 /// sequence that the iterator exposes.
 pub fn freq_count<T, U>(iter: T) -> hash_map::HashMap<U, uint>
-  where T: Iterator<Item=U>, U: Eq + Clone + Hash<Hasher>
+  where T: Iterator<Item=U>, U: Eq + Clone + Hash
 {
     let mut map: hash_map::HashMap<U,uint> = hash_map::HashMap::new();
     for elem in iter {