Generate random BigUints and BigInts
test the correct function (oops)
Forgot to make accept() home for IO
Make I/O tests use run_in_mt_newsched_task to get more multi-threaded test coverage
Incorporate feedback from huonw

- use identifiers with underscores to avoid unused variable warning
- implement on R: Rng instead of on R: RngUtil
- bugfix: zero BigInts were being generated twice as often as any
  other number
- test that gen_biguint(0) always returns zero
Add with_mem_writer to std::rt::io::mem.

This is in many ways a replacement for the current
std::io::with_str_writer.
Update for_expr docs.
Merge RandBigUint and RandBigInt into single trait
debuginfo: Wrapped namespace facilities of llvm::DIBuilder
debuginfo: Support for namespaces (functions only)
debuginfo: Support for namespaces for types
rustpkg: Pass command-line arguments to rustc

rustpkg now accepts most of rustc's command-line arguments and passes
them along to rustc when building or installing.

A few rarely-used arguments aren't implemented yet.

rustpkg doesn't support flags that don't make sense with rustpkg
(for example, --bin and --lib, which get inferred from crate file names).

Closes #8522
auto merge of #9007 : dcrewi/rust/random-bigints, r=huonw
auto merge of #9107 : catamorphism/rust/rustpkg-command-line-flags, r=brson

r? @brson rustpkg now accepts most of rustc's command-line arguments and passes
them along to rustc when building or installing.

A few rarely-used arguments aren't implemented yet.

rustpkg doesn't support flags that don't make sense with rustpkg
(for example, --bin and --lib, which get inferred from crate file names).

Closes #8522
debuginfo: Renamed NamespaceTree to NamespaceTreeNode.
auto merge of #9097 : michaelwoerister/rust/namespaces, r=jdm

Who would have thought that namespaces are such a can of worms `:P` This is mostly because of some GDB idiosyncrasies (does not use namespace information but linkage-name attributes for displaying items contained in namespaces, also cannot handle functions lexically nested within functions), monomorphization, and information about external items only available from metadata.

This pull request tries to tackle the problem anyway:
* The `DW_AT_linkage_name` for functions is generated just to make GDB display a proper namespace-enabled function name. To this end, a pseudo-mangled name is generated, not corresponding to the real linkage name. This approach shows some success and could be extended to make GDB also show proper parameter types.
* As GDB won't accept subprogram DIEs nested within other subprogram DIEs, the `debuginfo` module now generates a *companion namespace* for each functions (iff needed). A function `fn abc()` will get a companion namespace with name `abc()`, which contains all items (modules, types, functions) declared within the functions scope. The real, proper solution, in my opinion, would be to faithfully reflect the program's lexical structure within DWARF (which allows arbitrary nesting of DIEs, afaik), but I am not sure LLVM's source level debugging implementation would like that and I am pretty sure GDB won't support this in the foreseeable future.
* Monomorphization leads to functions and companion namespaces like `somelib::some_func<int, float>()::some_other_function<bool, bool, bool>()`, which I think is the desired behaviour. There is some design space here, however. Maybe you people prefer `somelib::some_func()::some_other_function<bool, bool, bool>()` or `somelib::some_func()::some_other_function::<int, float, bool, bool, bool>()`.

The solution will work for now but there are a few things on my 'far future wish list':
* A real specification somewhere, what language constructs are mapped to what DWARF structures.
* Proper tests that directly compare the generated DWARF information to the expected results (possibly using something like [pyelftools](https://github.com/eliben/pyelftools) or llvm-dwarfdump)
* A unified implementation for crate-local and crate-external items (which would possibly involve beefing up `ast_map::path` and metadata a bit)

Any comments are welcome!

Closes #1541
Closes #1542 (there might be other issues with function name prettiness, but this specific issue should be fixed)
Closes #7715 (source locations for structs and enums are now read correctly from the AST)
auto merge of #9039 : singingboyo/rust/update-for-expr-docs, r=thestinger

The old documentation for for loops/expressions has been quite wrong since the change to iterators.  This updates the docs to make them relevant to how for loops work now, if not very in-depth.  There may be a need for updates giving more depth on how they work, such as detailing what method calls they make, but I don't know enough about the implementation to include that.
auto merge of #8999 : anasazi/rust/multi-threaded-io-tests, r=brson

Resolves #8685
Properly encode/decode structural variants.
Rename encode_struct_field_names to encode_struct_fields to reflect what it actually does