fix cross-crate destructor inlining

Closes #7793
auto merge of #10242 : thestinger/rust/inline_dtor, r=alexcrichton

Closes #7793
replace RetVoid with Unreachable to fix lint

The function is marked `noreturn`, so it shouldn't return.
auto merge of #10244 : thestinger/rust/abort, r=alexcrichton

The function is marked `noreturn`, so it shouldn't have this.
Rename files to match current recommendations.

New standards have arisen in recent months, mostly for the use of
rustpkg, but the main Rust codebase has not been altered to match these
new specifications. This changeset rectifies most of these issues.

- Renamed the crate source files `src/libX/X.rs` to `lib.rs`, for
  consistency with current styles; this affects extra, rustc, rustdoc,
  rustpkg, rustuv, std, syntax.

- Renamed `X/X.rs` to `X/mod.rs,` as is now recommended style, for
  `std::num` and `std::terminfo`.

- Shifted `src/libstd/str/ascii.rs` out of the otherwise unused `str`
  directory, to be consistent with its import path of `std::ascii`;
  libstd is flat at present so it's more appropriate thus.

While this removes some `#[path = "..."]` directives, it does not remove
all of them, and leaves certain other inconsistencies, such as `std::u8`
et al. which are actually stored in `src/libstd/num/` (one subdirectory
down). No quorum has been reached on this issue, so I felt it best to
leave them all alone at present. #9208 deals with the possibility of
making libstd more hierarchical (such as changing the crate to match the
current filesystem structure, which would make the module path
`std::num::u8`).

There is one thing remaining in which this repository is not
rustpkg-compliant: rustpkg would have `src/std/` et al. rather than
`src/libstd/` et al. I have not endeavoured to change that at this point
as it would guarantee prompt bitrot and confusion. A change of that
magnitude needs to be discussed first.
auto merge of #10143 : chris-morgan/rust/filename-consistency, r=huonw

New standards have arisen in recent months, mostly for the use of
rustpkg, but the main Rust codebase has not been altered to match these
new specifications. This changeset rectifies most of these issues.

- Renamed the crate source files `src/libX/X.rs` to `lib.rs`, for
  consistency with current styles; this affects extra, rustc, rustdoc,
  rustpkg, std, syntax.

- Renamed `X/X.rs` to `X/mod.rs,` as is now recommended style, for
  `std::num` and `std::terminfo`.

- Shifted `src/libstd/str/ascii.rs` out of the otherwise unused `str`
  directory, to be consistent with its import path of `std::ascii`;
  libstd is flat at present so it's more appropriate thus.

While this removes some `#[path = "..."]` directives, it does not remove
all of them, and leaves certain other inconsistencies, such as `std::u8`
et al. which are actually stored in `src/libstd/num/` (one subdirectory
down). No quorum has been reached on this issue, so I felt it best to
leave them all alone at present. #9208 deals with the possibility of
making libstd more hierarchical (such as changing the crate to match the
current filesystem structure, which would make the module path
`std::num::u8`).

There is one thing remaining in which this repository is not
rustpkg-compliant: rustpkg would have `src/std/` et al. rather than
`src/libstd/` et al. I have not endeavoured to change that at this point
as it would guarantee prompt bitrot and confusion. A change of that
magnitude needs to be discussed first.
Move rt::io traits into the prelude

These traits belong here, and were simply waiting for the std::io traits to get
removed. It's time they take their rightful positions!
Modify IoFactory's fs_mkdir, and add fs_rename

The invocation for making a directory should be able to specify a mode to make
the directory with (instead of defaulting to one particular mode). Additionally,
libuv and various OSes implement efficient versions of renaming files, so this
operation is exposed as an IoFactory call.
Remove all blocking std::os blocking functions

This commit moves all thread-blocking I/O functions from the std::os module.
Their replacements can be found in either std::rt::io::file or in a hidden
"old_os" module inside of native::file. I didn't want to outright delete these
functions because they have a lot of special casing learned over time for each
OS/platform, and I imagine that these will someday get integrated into a
blocking implementation of IoFactory. For now, they're moved to a private module
to prevent bitrot and still have tests to ensure that they work.

I've also expanded the extensions to a few more methods defined on Path, most of
which were previously defined in std::os but now have non-thread-blocking
implementations as part of using the current IoFactory.

The api of io::file is in flux, but I plan on changing it in the next commit as
well.

Closes #10057
Fill out the remaining functionality in io::file

This adds bindings to the remaining functions provided by libuv, all of which
are useful operations on files which need to get exposed somehow.

Some highlights:

* Dropped `FileReader` and `FileWriter` and `FileStream` for one `File` type
* Moved all file-related methods to be static methods under `File`
* All directory related methods are still top-level functions
* Created `io::FilePermission` types (backed by u32) that are what you'd expect
* Created `io::FileType` and refactored `FileStat` to use FileType and
  FilePermission
* Removed the expanding matrix of `FileMode` operations. The mode of reading a
  file will not have the O_CREAT flag, but a write mode will always have the
  O_CREAT flag.

Closes #10130
Closes #10131
Closes #10121
Move io::file to io::fs and fns out of File

This renames the `file` module to `fs` because that more accurately describes
its current purpose (manipulating the filesystem, not just files).

Additionally, this adds an UnstableFileStat structure as a nested structure of
FileStat to signify that the fields should not be depended on. The structure is
currently flagged with #[unstable], but it's unlikely that it has much meaning.