Add [mut_]shift_ref/[mut_]pop_ref functions, which return a pointer to the first/last item in the slice and modify the slice to exclude the returned item. Useful when writing iterators over mutable references.
Remove the unused obsolete enum_discrim type.
Remove unused std::routine
auto merge of #10677 : jld/rust/type-enum-discrim-rm, r=alexcrichton
Remove enum struct return workaround from LLVM bindings.
std::ascii:  Fix is_digit() and is_control()

is_digit() incorrectly returned false for '0'.
is_control() incorrectly returned true for ' ' (space).
auto merge of #10679 : alexcrichton/rust/no-routine, r=pcwalton
Shink NodeId, CrateNum, Name and Mrk down to 32 bits on x64.
Add an iterator for receiving messages from GenericPorts
Clean up statically initialized data on shutdown

Whenever the runtime is shut down, add a few hooks to clean up some of the
statically initialized data of the runtime. Note that this is an unsafe
operation because there's no guarantee on behalf of the runtime that there's no
other code running which is using the runtime.

This helps turn down the noise a bit in the valgrind output related to
statically initialized mutexes. It doesn't turn the noise down to 0 because
there are still statically initialized mutexes in dynamic_lib and
os::with_env_lock, but I believe that it would be easy enough to add exceptions
for those cases and I don't think that it's the runtime's job to go and clean up
that data.
auto merge of #10670 : eddyb/rust/node-u32, r=alexcrichton

### Rationale
There is no reason to support more than 2³² nodes or names at this moment, as compiling something that big (even without considering the quadratic space usage of some analysis passes) would take at least **64GB**.
Meanwhile, some can't (or barely can) compile rustc because it requires almost **1.5GB**.

### Potential problems
Can someone confirm this doesn't affect metadata (de)serialization? I can't tell myself, I know nothing about it.

### Results
Some structures have a size reduction of 25% to 50%: [before](https://gist.github.com/luqmana/3a82a51fa9c86d9191fa) - [after](https://gist.github.com/eddyb/5a75f8973d3d8018afd3).
Sadly, there isn't a massive change in the memory used for compiling stage2 librustc (it doesn't go over **1.4GB** as [before](http://huonw.github.io/isrustfastyet/mem/), but I can barely see the difference).
However, my own testcase (previously peaking at **1.6GB** in typeck) shows a reduction of **200**-**400MB**.
Add benchmark tests to path/posix

I have written some benchmark tests to `push`, `push_many`, `join`,
`join_many` and `ends_with_path`.
auto merge of #10688 : bjz/rust/recv_iter, r=brson

I've noticed I use this pattern quite a bit:

~~~rust
do spawn {
    loop {
        match port.try_recv() {
            Some(x) => ...,
            None => ...,
        }
    }
}
~~~

The `RecvIterator`, returned from a default `recv_iter` method on the `GenericPort` trait, allows you to reduce this down to:

~~~rust
do spawn {
    for x in port.recv_iter() {
        ...
    }
}
~~~

As demonstrated in the tests, you can also access the port from within the `for` block for further `recv`ing and `peek`ing with no borrow errors, which is quite nice.
auto merge of #10684 : jld/rust/unstruct-unhack-typekind, r=alexcrichton
Freeze the AST by removing a couple of unused @mut ~[T] from token_tree.
std::ascii:  Add tests for is_digit() and is_control()
auto merge of #10693 : eddyb/rust/freeze-ast, r=thestinger

It's truly immutable now, which will allow us to remove some cloning in the parser and box parts of the AST in `Rc<T>` (if desired).
rustdoc: Use new ||/proc syntax
Improve the rt::thread module

* Added doc comments explaining what all public functionality does.
* Added the ability to spawn a detached thread
* Added the ability for the procs to return a value in 'join'
Relax restrictions on unknown feature directives

Instead of forcibly always aborting compilation, allow usage of
 #[warn(unknown_features)] and related lint attributes to selectively abort
 compilation. By default, this lint is deny.