Add IoctlGetInt/IoctlSetInt, IoctlGetTermios/IoctlSetTermios and
IoctlGetWinsize/IoctlSetWinsize on FreeBSD. These are similar to the
already existing implementations on Linux, Darwin and Solaris.

Generated on FreeBSD 10.11-RELEASE.

Change-Id: I79b273032cfeb719ec5550ac15635fd9f3231469
Reviewed-on: https://go-review.googlesource.com/52710Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>