unix: add ioctl functions on FreeBSD

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/52710
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/unix/ztypes_freebsd_amd64.go b/unix/ztypes_freebsd_amd64.go
index d987a00..c65d89e 100644
--- a/unix/ztypes_freebsd_amd64.go
+++ b/unix/ztypes_freebsd_amd64.go
@@ -505,6 +505,13 @@
 	Ospeed uint32
 }
 
+type Winsize struct {
+	Row    uint16
+	Col    uint16
+	Xpixel uint16
+	Ypixel uint16
+}
+
 const (
 	AT_FDCWD            = -0x64
 	AT_REMOVEDIR        = 0x800