Add new FreeBSD socket option SO_REUSEPORT_LB.

FreeBSD 12, which is scheduled to be released soon, has a new socket option SO_REUSEPORT_LB.
From setsockopt man page:
     SO_REUSEPORT_LB allows completely duplicate bindings by multiple
     processes if they all set SO_REUSEPORT_LB before binding the port.
     Incoming TCP and UDP connections are distributed among the sharing
     processes based on a hash function of local port number, foreign IP
     address and port number. A maximum of 256 processes can share one socket.

Fix mips-unknown-linux-uclibc target

The mips(el)-unknown-linux-uclibc target has apparently been broken in one way or another for over a year. This PR is the patch it took to successfully build a beta toolchain that could support it.

I am pretty sure these fixes are the right answer, after considerable digging in both the libc crate source (_pub-use pub-use everywhere, and not a hint to link_) and the uClibc source (_it's not POSIX, but they've shipped it since 2007, so close enough_).

For those who don't know, the *-uClibc targets are the only way (AFAIK) to create Rust binaries which run on Linux kernels prior to 2.6. It is a use case that is getting quite rare these days, but is still present in embedded ecosystems where chip vendors never migrated their hardware support to newer kernel versions.

Here's hoping these Rust toolchain targets find a maintainer someday.

cc rust-lang/rust#43503

Add a couple more ELF types

Add some more elf types

Add mallopt

First time contributor. Thanks for the excellent contributing guide.
I'm not quite sure I put the method in the right place. [The GNULib docs](https://www.gnu.org/software/gnulib/manual/html_node/mallopt.html) say its not on Android 7.1, but there are [mentions of it in some android headers](https://android.googlesource.com/platform/bionic/+/master/libc/include/malloc.h).

Add additional Redox OS functions

This adds `chown`, `fchown`, `setenv`, and `unsetenv` to the `redox` module, and reorders the functions by name

Undo division of in6_addr on Fuchsia

sparc64 tests are passing again

Closes #1064 .

Closes #1064 .

Fix and cleanup Fuchsia

Remove false support for power and mips.
Fix aarch64 definitions of nlink_t and blksize_t.

r? @alexcrichton

cc @sulanov

Remove false support for power and mips.
Fix aarch64 definitions of nlink_t and blksize_t.

Add TIOCGWINSZ accessor to solaris module

Signed-off-by: Ian Henry <ihenry@chef.io>

I recently noticed downstream that these request values were unavailable and needed for things like [the pb crate](https://github.com/a8m/pb). To get access to the request value I ran the following simple C code:
```
#include <sys/ioctl.h>
#include <stdio.h>
#include <sys/termios.h>

int main(int argc, char **argv) {
    printf("Code: 0x%04lx\n", TIOCGWINSZ);
    printf("Code: 0x%04lx\n", TIOCSWINSZ);
    return 0;
}
```
To then validate the change I ran the following simple rust:
```
extern crate libc;

use libc::{ioctl, winsize, STDOUT_FILENO, TIOCGWINSZ};

fn main() {
    let mut wsize = winsize {
        ws_row: 0,
        ws_col: 0,
        ws_xpixel: 0,
        ws_ypixel: 0,
    };
    unsafe {
        ioctl(STDOUT_FILENO, TIOCGWINSZ, &mut wsize);
    }
    println!("Sizes: {{ rows: {}, cols: {}, xpixel: {}, ypixel: {} }}",
             wsize.ws_row,
             wsize.ws_col,
             wsize.ws_xpixel,
             wsize.ws_ypixel);
}
```

Signed-off-by: Ian Henry <ihenry@chef.io>

NetBSD: correct link_name of some time-related functions

Add exchangedata for osx

The futimes(), lutimes(), mq_timedreceive(), and mq_timedsend()
functions were linking against legacy library symbols that need 32-bit
time_t in structures, resulting in an ABI mismatch with 64-bit time_t.

Update ctest to 0.2

Add libc definitions for Megaton-Hammer, a Switch Homebrew toolchain

I'm working on a pure-rust toolchain to write homebrew for the Nintendo Switch called [Megaton-Hammer](http://github.com/megatonhammer/megaton-hammer). I'm hoping to get those definitions upstreamed to simplify my life :).

This toolchain does not depend on a C compiler or a libc (it reimplements everything in rust) - but given many crates in the Rust ecosystem rely on the libc crate for the definition of various common types, this is what I came up with.

I was wondering what a good target triple would be ? I currently gate the implementation behind `target_os = "switch"`, but if this goes upstream I figure that might cause trouble for people using the Nintendo SDK (they might already be using `target_os = "switch"` for some things). Would it be better to go with `target_env = "megatonhammer"`?

NetBSD: add basic types for aarch64