Auto merge of #293 - SShrike:freebsd-ioctl-constants, r=alexcrichton
Auto merge of #293 - SShrike:freebsd-ioctl-constants, r=alexcrichton

Add the TIOCGWINSZ and TIOCSWINSZ constants

I've added the `TIOCGWINSZ` and `TIOCSWINSZ` constants/ioctl control codes. I wasn't quite sure where to put them, so hopefully they're in the right place.

As of now it's set to compile on 'FreeBSD-like' platforms, so it will compile on both FreeBSD *and* DragonflyBSD. I've only tested it on FreeBSD though, but it should also work on DragonflyBSD AFAIK.

Fixes #292.

cactorium/libc,anatol/libc,zethra/libc,philippkeller/libc,philippkeller/libc,philippkeller/libc,rust-lang/libc,anatol/libc,rust-lang-nursery/libc,rust-lang/libc,mneumann/libc,superriva/libc,cactorium/libc,zethra/libc,cactorium/libc,rust-lang-nursery/libc,mneumann/libc,zethra/libc,superriva/libc,rust-lang/libc,rust-lang-nursery/libc,mneumann/libc,superriva/libc,anatol/libc