syntax: Fix parsing << with closure types

This uses the trick of replacing the << token with a < token to parse closure
types correctly.

Closes #13324
test: Fix a pretty printing test

The pretty printer handles inlines comments quite badly
test: Ignore a pretty expanded failing test

When expanding, an extra unsafe block is generated which is currently not
handled well.
syntax: Print suffixed token literals correctly

Previously, literals "1i" were printed as "1". This fixes the
numeric-method-autoexport test for pretty printing.
test: Give a test a bigger stack for pretty printing
syntax: Preserve attributes in #[deriving]

Now that the #[deriving] attribute is removed, the raw_pointers_deriving lint
was broken. This commit restores the lint by preserving lint attributes
across #[deriving] to the implementations and using #[automatically_derived] as
the trigger for activating the lint.
syntax: Improve --pretty normal slightly

When printing doc comments, always put a newline after them in a macro
invocation to ensure that a line-doc-comment doesn't consume remaining tokens on
the line.
rustllvm: Add LLVMRustArrayType

LLVM internally uses `uint64_t` for array size, but the corresponding
C API (`LLVMArrayType`) uses `unsigned int` so ths value is truncated.
Therefore rustc generates wrong type for fixed-sized large vector e.g.
`[0 x i8]` for `[0u8, ..(1 << 32)]`.

This patch adds `LLVMRustArrayType` function for `uint64_t` support.
io: Implement process wait timeouts

This implements set_timeout() for std::io::Process which will affect wait()
operations on the process. This follows the same pattern as the rest of the
timeouts emerging in std::io::net.

The implementation was super easy for everything except libnative on unix
(backwards from usual!), which required a good bit of signal handling. There's a
doc comment explaining the strategy in libnative. Internally, this also required
refactoring the "helper thread" implementation used by libnative to allow for an
extra helper thread (not just the timer).

This is a breaking change in terms of the io::Process API. It is now possible
for wait() to fail, and subsequently wait_with_output(). These two functions now
return IoResult<T> due to the fact that they can time out.

Additionally, the wait_with_output() function has moved from taking `&mut self`
to taking `self`. If a timeout occurs while waiting with output, the semantics
are undesirable in almost all cases if attempting to re-wait on the process.
Equivalent functionality can still be achieved by dealing with the output
handles manually.

[breaking-change]

cc #13523
auto merge of #14187 : alexcrichton/rust/rollup, r=alexcrichton

Closes #14184 (std: Move the owned module from core to std)
Closes #14183 (Allow blocks in const expressions)
Closes #14176 (Add tests for from_bits.)
Closes #14175 (Replaced ~T by Box<T> in manual)
Closes #14173 (Implements Default trait for BigInt and BigUint)
Closes #14171 (Fix #8391)
Closes #14159 (Clean up unicode code in libstd)
Closes #14126 (docs: Add a not found page)
Closes #14123 (add a line to the example to clarify semantics)
Closes #14106 (Pretty printer improvements)
Closes #14083 (rustllvm: Add LLVMRustArrayType)
Closes #13957 (io: Implement process wait timeouts)
io: Add .read_at_least() to Reader

Reader.read_at_least() ensures that at least a given number of bytes
have been read. The most common use-case for this is ensuring at least 1
byte has been read. If the reader returns 0 enough times in a row, a new
error kind NoProgress will be returned instead of looping infinitely.

This change is necessary in order to properly support Readers that
repeatedly return 0, either because they're broken, or because they're
attempting to do a non-blocking read on some resource that never becomes
available.

Also add .push() and .push_at_least() methods. push() is like read() but
the results are appended to the passed Vec.

Remove Reader.fill() and Reader.push_exact() as they end up being thin
wrappers around read_at_least() and push_at_least().

[breaking-change]
auto merge of #13127 : kballard/rust/read_at_least, r=alexcrichton

Reader.read_at_least() ensures that at least a given number of bytes
have been read. The most common use-case for this is ensuring at least 1
byte has been read. If the reader returns 0 enough times in a row, a new
error kind NoProgress will be returned instead of looping infinitely.

This change is necessary in order to properly support Readers that
repeatedly return 0, either because they're broken, or because they're
attempting to do a non-blocking read on some resource that never becomes
available.

Also add .push() and .push_at_least() methods. push() is like read() but
the results are appended to the passed Vec.

Remove Reader.fill() and Reader.push_exact() as they end up being thin
wrappers around read_at_least() and push_at_least().

[breaking-change]
auto merge of #14178 : alexcrichton/rust/more-ignores, r=brson

It was thought that these failures only happened on windows, turns out they
happen on any 32-bit machine.

cc #14064
Get rid of the android-cross-path flag to rustc.

There's no need to include this specific flag just for android. We can
already deal with what it tries to solve by using -C linker=/path/to/cc
and -C ar=/path/to/ar. The Makefiles for rustc already set this up when
we're crosscompiling.

I did add the flag to compiletest though so it can find gdb. Though, I'm
pretty sure we don't run debuginfo tests on android anyways right now.

[breaking-change]
librustc: Make sure to add argument attributes to extern fns from non-local crates.
Removed unnecessary arguments for walk_* functions
core: Inherit the atomics module
core: Add a crate doc block
core: Document should_not_exist's existence

Explain why it should not exist, and the plan of attack for removing it.
core: Allow using failure outside of libcore

Due to our excellent macro hygiene, this involves having a global path and a
hidden module in libcore itself.