native: Fix a possible deadlock in spawn

The OSX bots have been deadlocking recently in the rustdoc tests. I have only
been able to rarely reproduce the deadlock on my local setup. When reproduced,
it looks like the child process is spinning on the malloc mutex, which I
presume is locked with no other threads to unlock it.

I'm not convinced that this is what's happening, because OSX should protect
against this with pthread_atfork by default. Regardless, running as little code
as possible in the child after fork() is normally a good idea anyway, so this
commit moves all allocation to the parent process to run before the child
executes.

After running 6k iterations of rustdoc tests, this deadlocked twice before, and
after 20k iterations afterwards, it never deadlocked. I draw the conclusion that
this is either sweeping the bug under the rug, or it did indeed fix the
underlying problem.
std: Add an I/O reader method to fill a buffer

I've found a common use case being to fill a slice (not an owned vector)
completely with bytes. It's posible for short reads to happen, and if you're
trying to get an exact number of bytes then this helper will be useful.
rand: Use fill() instead of read()

It's possible for a reader to have a short read, and there's no reason the task
should fail in this scenario. By using fill(), this has a stronger guarantee
that the buffer will get filled with data.
Snapshot cleanup
std: Move NativeMutex from &mut self to &self

The proper usage of shared types is now sharing through `&self` rather than
`&mut self` because the mutable version will provide stronger guarantees (no
aliasing on *any* thread).
sync: Move the concurrent queue to using &self

This commit also lifts it up a level in the module hierarchy in the soon-to-come
reorganization of libsync.
sync: Move the Mutex type to using &self

This also uses the Unsafe type for any interior mutability in the type to avoid
transmutes.
sync: Move Once to using &self

Similarly to the rest of the previous commits, this moves the once primitive to
using &self instead of &mut self for proper sharing among many threads now.
sync: Rewrite the base primitives

This commit rewrites the core primitives of the sync library: Mutex, RWLock, and
Semaphore. These primitives now have updated, more modernized apis:

* Guards are returned instead of locking with closures. All condition variables
  have moved inside the guards and extraneous methods have been removed.
* Downgrading on an rwlock is now done through the guard instead of the rwlock
  itself.

These types are meant to be general locks, not locks of an internal type (for
external usage). New types will be introduced for locking shared data.
sync: Introduce new wrapper types for locking

This introduces new synchronization types which are meant to be the foundational
building blocks for sharing data among tasks. The new Mutex and RWLock types
have a type parameter which is the internal data that is accessed. Access to the
data is all performed through the guards returned, and the guards all have
autoderef implemented for easy access.
docs: named lifetimes

* Include tip given by Leo Testard in mailing list about labeled `break`
and `continue`:
https://mail.mozilla.org/pipermail/rust-dev/2014-March/009145.html
* cross-reference named lifetimes in tutorial -> lifetimes guide
* Broke named lifetimes section into two sub-sections.
* Added mention of `'static` lifetime.
Added suggested notes

* Note on while loop not supporting named breaks.
* Note on hygienic macros (and example of such within loops)
Correct overly broad definition of `'static` kind bound.

While double-checking my understanding of the meaning of `'static`,
I made the following test program:

```rust
fn foo<X:'static>(_x: X) { }

#[cfg(not(acceptable))]
fn bar() {
    let a = 3;
    let b = &a;
    foo(b);
}

#[cfg(acceptable)]
fn bar() {
    static c : int = 4;;
    let d : &'static int = &c;
    foo(d);
}

fn main() {
    bar();
}
```

Transcript of compiling above program, illustrating that the `--cfg
acceptable` variant of `bar` compiles successfully, showing that the
`'static` kind bound only disallows non-`static` references, not *all*
references:

```
% rustc --version
/Users/fklock/opt/rust-dbg/bin/rustc 0.10-pre (caf17fe 2014-03-21 02:21:50 -0700)
host: x86_64-apple-darwin
% rustc /tmp/s.rs
/tmp/s.rs:7:5: 7:8 error: instantiating a type parameter with an incompatible type `&int`, which does not fulfill `'static`
/tmp/s.rs:7     foo(b);
                ^~~
error: aborting due to previous error
% rustc --cfg acceptable /tmp/s.rs
% ./s
%
```

(Note that the explicit type annotation on `let d : &'static int` is
necessary; it did not suffice for me to just write `let d = &'static
c;`.  That might be a latent bug, I am not sure yet.)

Anyway, a fix to the documentation seemed prudent.
auto merge of #13113 : pnkfelix/rust/correct-static-kind-doc, r=huonw

While double-checking my understanding of the meaning of `'static`, I made the following test program:

```rust
fn foo<X:'static>(_x: X) { }

#[cfg(not(acceptable))]
fn bar() {
    let a = 3;
    let b = &a;
    foo(b);
}

#[cfg(acceptable)]
fn bar() {
    static c : int = 4;;
    let d : &'static int = &c;
    foo(d);
}

fn main() {
    bar();
}
```

Transcript of compiling above program, illustrating that the `--cfg acceptable` variant of `bar` compiles successfully, showing that the`'static` kind bound only disallows non-`static` references, not *all* references:

```
% rustc --version
/Users/fklock/opt/rust-dbg/bin/rustc 0.10-pre (caf17fe 2014-03-21 02:21:50 -0700)
host: x86_64-apple-darwin
% rustc /tmp/s.rs
/tmp/s.rs:7:5: 7:8 error: instantiating a type parameter with an incompatible type `&int`, which does not fulfill `'static`
/tmp/s.rs:7     foo(b);
                ^~~
error: aborting due to previous error
% rustc --cfg acceptable /tmp/s.rs
% ./s
%
```

(Note that the explicit type annotation on `let d : &'static int` is necessary; it did not suffice for me to just write `let d = &'static c;`. That might be a latent bug, I am not sure yet.)

Anyway, a fix to the documentation seemed prudent.
rustc: Completely forbid borrows of unsafe statics

Summary:
It was possible to borrow unsafe static items in static initializers.
This patch implements a small `Visitor` that walks static initializer's
expressions and checks borrows aliasability.

Fixes #13005

Test Plan: make check

Differential Revision: http://phabricator.octayn.net/D2
green: Remove the dependence on the crate map

This is the final nail in the coffin for the crate map. The `start` function for
libgreen now has a new added parameter which is the event loop factory instead
of inferring it from the crate map. The two current valid values for this
parameter are `green::basic::event_loop` and `rustuv::event_loop`.
rustc: Remove all crate map support

The crate map is no longer necessary now that logging and event loop factories
have been moved out.

Closes #11617
Closes #11731
doc: Update the runtime guide with green changes

This updates a few code examples about booting libgreen/libnative and also
spells out how the event loop factory is required.
auto merge of #13049 : alexcrichton/rust/io-fill, r=huonw

This method can be used to fill a byte slice of data entirely, and it's considered an error if any error happens before its entirely filled.
mk: Stop building OS X .pkg as part of 'make dist'

This doesn't work quite right yet (we need to build packages for all hosts)
and I'm not ready to turn on new dist artifacts yet, but I want to start doing
dry runs for 0.10, so I'm turning this off for now.