Don't make tags for our dependencies and tests.

Largely, this is just being more specific about where tags get searched
for to remove external dependencies like src/llvm, which reduces the
number of tags *enormously* and significantly increases the usefulness
of the tags file as it is then focusing on 240K lines of Rust code
and 4.5K of C++ rather than just shy of 1M lines of C++ code (mostly
from LLVM) and another 100K lines of Rust tests and a diverse collection
of other languages.

src/rustllvm/RustWrapper.cpp and src/rustllvm/PassWrapper.cpp are
getting tags made, but I'm not sure if that's desirable or not. At
worst, it's not a significant wrong.

A future, desirable step is producing tags for just libstd and libextra
for the use of people using Rust-the-language rather than working on
Rust itself.
fix 10468, propagate optimization level as rustc::driver::session::OptLevel
Fixed uses of get() to unwrap() in doc examples in std::iter
Fixed docs for advance() in Iterator trait
auto merge of #10533 : tautologico/rust/fixdocs, r=huonw

This fixes a number of bugs in the doc comments for a bunch of functions in libstd/iter.rs, mostly updating to use unwrap() instead of get() on options. Also fixes the docs for advance() (trait Iterator) which was not making sense, though if it is not useful anymore maybe it should be removed.
Fix XFailed test x86stdcall

There was a syntax error because the `extern "stdcall"` was outside the module instead of inside it.

* moved `extern` inside module
* change `extern "stdcall"` to `extern "system"`
* change `cfg(target_os="win32")` to `cfg(windows)`
* updated copyright dates
* changed log(error, ...) => info!(....)
* added `pub` keyword to kernel32 functions
auto merge of #10363 : astrieanna/rust/fix-x86stdcall, r=huonw

* moved `extern` inside module
* changed `extern "stdcall"` to `extern "system"`
* changed `cfg(target_os="win32")` to `cfg(windows)`
* only run on Windows && x86, (not x86_64)
* updated copyright dates
auto merge of #10526 : itdaniher/rust/master, r=pcwalton

This commit fixes issue #10468.

It propagate optimization level from PkgSrc to compile_crate as a rustc::driver::session::OptLevel enum.

The 'opt' argument to compile_crate was previously hardcoded as boolean false, such that calls to session::options would always result in the session::No flag being used.
Forbid privacy in inner functions

Closes #10111
auto merge of #10443 : alexcrichton/rust/meaninless-pub-priv, r=cmr

Closes #10111
auto merge of #10508 : chris-morgan/rust/tags-improvements, r=cmr

Largely, this is just being more specific about where tags get searched
for to remove external dependencies like src/llvm, which reduces the
number of tags *enormously* and significantly increases the usefulness
of the tags file as it is then focusing on 240K lines of Rust code
and 4.5K of C++ rather than just shy of 1M lines of C++ code (mostly
from LLVM) and another 100K lines of Rust tests and a diverse collection
of other languages.

src/rustllvm/RustWrapper.cpp and src/rustllvm/PassWrapper.cpp are
getting tags made, but I'm not sure if that's desirable or not. At
worst, it's not a significant wrong.

A future, desirable step is producing tags for just libstd and libextra
for the use of people using Rust-the-language rather than working on
Rust itself.
std::rand: wrappers for floats from [0,1] and (0,1).

Provide `Closed01` and `Open01` that generate directly from the
closed/open intervals from 0 to 1, in contrast to the plain impls for
f32 and f64 which generate the half-open [0,1).

Fixes #7755.
debuginfo: Improved stepping for if-expressions
Don't mark reachable extern fns as internal

If a function is marked as external, then it's likely desired for use with some
native library, so we're not really accomplishing a whole lot by internalizing
all of these symbols.
auto merge of #10539 : alexcrichton/rust/external-linkage, r=pcwalton

If a function is marked as external, then it's likely desired for use with some
native library, so we're not really accomplishing a whole lot by internalizing
all of these symbols.
pidigits resurected

Changes:
* default value when no args
* license
* removed libc printing
* use extra::bigint instead of handmade gmp binding
auto merge of #10555 : TeXitoi/rust/pidigits-resurected, r=alexcrichton

Changes:
* default value when no args
* license
* removed libc printing
* use extra::bigint instead of handmade gmp binding

The drawback is that it's 2 order of magnitude slower, the good news is that there is a good bench for extra::bigint.
auto merge of #10552 : michaelwoerister/rust/ifstepping, r=brson

This PR improves the single-stepping experience for if-expression (no more jumping into the *else* branch before entering the *then* branch, no more jumping to the end of the *else* branch after finishing the *then* branch). Unfortunately I don't know of a straight-forward way of writing automated tests for this. Suggestions welcome!
temporarily disable tests on android and tagging issue number #10455
fix #10450