add net/if_arp.h definitions

This is based on the contents of include/net/if_arp.h on my Linux system.

Add some termios constants for sparc64

Bump version to 0.2.42

Closes https://github.com/rust-lang/libc/issues/1011

make dox::mem::size_of a const fn

add more built-in traits to dox.rs

Add/fix bitwise operation traits in dox.rs

Fix sparc64 builds

Partially fixes #987.

add rtentry

Add `gethostname` support to Redox module

We need this for hostname support in Ion shell.

Add consts from netinet/ip.h

fix size_of function in dox.rs

I'm assuming this is meant to have the same signature as the one in core/std

Add linux socket ioctl defs

Moves `ifaddrs` and some functions to common Linux module

The `ifaddrs` interface is available since api version 24 in android.
The function signatures are now equal to the standard Linux function
signatures.

The `ifaddrs` interface is available since api version 24 in android.
The function signatures are now equal to the standard Linux function
signatures.

Add SIG* on redox