std: fix an infinite loop in num::ToPrimitive and add tests
Register new snapshots
auto merge of #9757 : erickt/rust/master, r=alexcrichton

I accidentally left an infinite loop in a default method in `num::ToPrimitive::to_u64()`. This fixes it.
auto merge of #9771 : alexcrichton/rust/snapshots, r=thestinger

Still building locally, we'll see if anything dies...
Build libuv/jemalloc only once (not per stage)

Reorganize the makefiles to stop building these once per stage because there's
no need to do this at all.

Closes #7002
auto merge of #9772 : alexcrichton/rust/buildsystem, r=thestinger

Reorganize the makefiles to stop building these once per stage because there's
no need to do this at all.

Closes #7002
Allow attributes on macros

It's unclear to me why these currently aren't allowed, and my best guess is that
a long time ago we didn't strip the ast of cfg nodes before syntax expansion.
Now that this is done, I'm not certain that we should continue to prohibit this
functionality.

This is a step in the right direction towards #5605, because now we can add an
empty `std::macros` module to the documentation with a bunch of empty macros
explaining how they're supposed to be used.
auto merge of #9753 : alexcrichton/rust/macro-attrs, r=brson

It's unclear to me why these currently aren't allowed, and my best guess is that
a long time ago we didn't strip the ast of cfg nodes before syntax expansion.
Now that this is done, I'm not certain that we should continue to prohibit this
functionality.

This is a step in the right direction towards #5605, because now we can add an
empty `std::macros` module to the documentation with a bunch of empty macros
explaining how they're supposed to be used.
Change default lint output format.

Since lint check attributes are the preferred way of selectively
enabling/disabling lint checks, the output format of a failed
default check has been changed to reflect that.

When lint checks are being explicitly set by a command-line flag
or an attribute, the behavior is unchanged, so that the user can
quickly pinpoint the source.

Closes #6580
Makefile: Get git revision correctly on Windows

Fixes a bug that `rustc.exe -v` didn't show git revision hash.
The bug is caused by that `$(wildcard $(CFG_GIT))` requires
space-escaped inputs while `$(CFG_GIT)` is usually
`C:\Program Files (x86)\Git\bin\git.exe`.
auto merge of #9782 : geoffhill/rust/lint-format2, r=alexcrichton

Since lint check attributes are the preferred way of selectively
enabling/disabling lint checks, the output format of a failed
default check has been changed to reflect that.

When lint checks are being explicitly set by a command-line flag
or an attribute, the behavior is unchanged, so that the user can
quickly pinpoint the source.

Supersedes the patch suggested in #9778
Closes #6580
std::rand: move the Isaac implementation to its own file.
std::rand: Add an implementation of ISAAC64.

This is 2x faster on 64-bit computers at generating anything larger
than 32-bits.

It has been verified against the canonical C implementation from the
website of the creator of ISAAC64.

Also, move `Rng.next` to `Rng.next_u32` and add `Rng.next_u64` to
take full advantage of the wider word width; otherwise Isaac64 will
always be squeezed down into a u32 wasting half the entropy and
offering no advantage over the 32-bit variant.
std::rand: Add OSRng, ReaderRng wrappers around the OS RNG & generic Readers respectively.

The former reads from e.g. /dev/urandom, the latter just wraps any
std::rt::io::Reader into an interface that implements Rng.

This also adds Rng.fill_bytes for efficient implementations of the above
(reading 8 bytes at a time is inefficient when you can read 1000), and
removes the dependence on src/rt (i.e. rand_gen_seed) although this last
one requires implementing hand-seeding of the XorShiftRng used in the
scheduler on Linux/unixes, since OSRng relies on a scheduler existing to
be able to read from /dev/urandom.
std::rand: add the StdRng wrapper for a blessed RNG.

This is implemented as a wrapper around another RNG. It is designed
to allow the actual implementation to be changed without changing
the external API (e.g. it currently uses a 64-bit generator on 64-
bit platforms, and a 32-bit one on 32-bit platforms; but one could
imagine that the IsaacRng may be deprecated later, and having this
ability to switch algorithms without having to update the points of
use is convenient.)

This is the recommended general use RNG.
std::rand: Add ReseedingRng, which will reseed an RNG after it generates a certain number of bytes.

It is an "RNG adaptor" and so any RNG can be wrapped to have this behaviour.
std::rand: Add a trait for seeding RNGs: SeedableRng.

This provides 2 methods: .reseed() and ::from_seed that modify and
create respecitively.

Implement this trait for the RNGs in the stdlib for which this makes
sense.
std::rand: improve the task_rng code.

It now:
- can be explicitly seeded from user code (`seed_task_rng`) or from the
  environment (`RUST_SEED`, a positive integer)
- automatically reseeds itself from the OS *unless* it was seeded by
  either method above
- has more documentation
std::rand: make the windows OSRng more correct, remove some C++.

This lets the C++ code in the rt handle the (slightly) tricky parts of
random number generation: e.g. error detection/handling, and using the
values of the `#define`d options to the various functions.
std::rand: add & split some tests.