MIPS32 and MIPS64 userspaces are mostly the same save the obvious ABI
difference, hence most of the const definitions could be shared.

This commit is not introducing any new significant additions, but mostly
just shuffles the existing files around to make the directory structure
more similar to the other, more mature platforms. The structs and extern
fn definitions are not touched. Plus a couple of new consts for MIPS64
to match MIPS32 coverage:

* `RLIM_INFINITY`
* `SYS_gettid`

Passed `libc-test` on Gentoo MIPS64el (n64 ABI), on a Loongson 3A2000
box. The test suite itself needs some more love to actually compile
cleanly on MIPS (`ctest` transitively depends on ancient `libc` version
which doesn't build on MIPS), but let's save that for another day.

POSIX AIO definitions, for BSD and Linux

musl has a different aiocb definition; netbsd and OSX have some symbol renaming, and
lwpid_t is signed on freebsd

Where structures included unions, I only defined the most useful member.  This
means that sigevents can't be delivered using SIGEV_THREAD until Rust gets better
union support (SIGEV_THREAD_ID still works).

Add ENOTSUP constant to more platforms.

Use `#[link(cfg(..))]` in preparation for libstd

In preparation for rust-lang/rust#37545 this is adding the appropriate
directives to libc to get included.

Minimal liblibc for Redox

add pledge(2) syscall.

Remove mipsel target_arches

The `mipsel` `target_arch` was introduced with the initial MIPSel
support (rust-lang/rust@82ec1aef293ddc5c6373bd7f5ec323fafbdf7901),
but was subsequently removed with implementation of the Flexible Target
Specification (Rust RFC 0131,
rust-lang/rust@3a8f4ec32a80d372db2d02c76acba0276c4effd0).
Remove these to be consistent with other arches and reduce confusion.

I've very slightly formatted the deletions so as to not require a style
cleanup later and obscure `git blame` output.

Update CI download location

Add setfsgid()/setfsuid() on linux

Fix typo in comment

Generate docs on 1.10.0

Should help us keep the size explosion under control.

Added tcsetpgrp

Enable musl with aarch64

Add setresuid/setresgid for linux

Signed-off-by: Dylan Reid <dgreid@chromium.org>

Add support for Fuchsia

Try to fix powerpc64 and update to crates.io ctest

This reverts commit 7ac91c6d.

Merge two separate config blocks for conditionally including ai_addr
in the addrinfo struct for unix/notbsd.