std: writing to stdout only works when using -1 offset..
std: UvFileStream implements HomingIO + .home_for_io() wrapper usage
rt: re-adding lines erroneous stripped out in merge conflict
std: naive stdio print test in uvio
std: more seek tests
change FileDescriptor instance methods to use &mut self
std: rename tmp file paths to go into ./tmp folder in builddir
std: reform fn sigs of FileDescriptor methods (better result signalling)
std: moved static file actions (open,unlink) to FsRequest
std: all of the calls in rt::uv::file take a &Loop
std: slight refactor on UvFilestream seek behavior, pre-seek-refactor
std: put FileMode/Access->whence-mask in uvio, open/unlink as fns in file::
make check appeasement
Update FFI tutorial to reference `c_str::to_c_str`

The FFI tutorial still incorrectly stated that strings were terminated
with \0 and suggested using `str::as_c_str`.
auto merge of #8659 : msullivan/rust/default-methods, r=alexcrichton
fix 32bit mac build error
make: rm LLVM_BUILD_ENV

using this to turn off the frame pointers isn't needed, and doesn't
actually work right now because the reference to it omits the target
triple
make: stop disabling frame pointer elimination

We currently have no need for the frame pointers on any platform. They
may eventually be needed on platforms without an equivalent to the DWARF
call frame information to walk the stack in the garbage collector.

Closes #7477
auto merge of #8655 : olsonjeffery/rust/newrt_file_io, r=pcwalton,brson

This PR includes the addition of the essential CRUD functionality exposed as a part of the `uv_fs_*` api. There's a lot more to be done, but the essential abstractions are in place and can be easily expanded.

A summary:

* `rt::io::file::FileStream` is fleshed out and behaves as a *non-positional* file stream (that is, it has a cursor that can be viewed/changed via `tell` and `seek`
* The underlying abstraction in `RtioFileStream` exposes pairs of `read(), write()` and `pread(), pwrite()`. The latter two take explicit `offset` params and don't respect the current cursor location in a file afaik. They both use the same underlying libuv impl
* Because libuv explicitly does *not* support `seek`/`tell` operations, these are impl'd in `UvFileStream` by using `lseek(2)` on the raw file descriptor.
* I did my best to flesh out and adhere to the stubbing that was already present in `rt::io::file` and the tests should back that up. There may be things missing.
* All of the work to test `seek`/`tell` is done in `rt::io::file`, even though the actual impl is down in `rt::uv::uvio`.
* We have the ability to spin up an `~RtioFileStream` from a raw file descriptor. This would be useful for interacting with stdin and stdout via newrt.
* The lowest level abstractions (in `rt::uv::file`) support fully synchronous/blocking interactions with the uv API and there is a CRUD test using it. This may also be useful for blocking printf, if desired (the default would be non-blocking and uses libuv's io threadpool)

There are a few polish things I need to do still (the foremost that I know of is undefined behavior when seek'ing beyond the file's boundary).

After this lands, I want to move on to mapping more of the `uv_fs_*` API (especially `uv_fs_stat`). Also a few people have mentioned interest in `uv_pipe_t` support. I'm open to suggestions.
removed os::set_args, closing #8325
removed pub on real_args, changed test to use args