go.crypto/ssh/terminal: add support for BSD variants

LGTM=agl
R=golang-codereviews, agl
CC=golang-codereviews
https://golang.org/cl/97850043

ssh/terminal/util.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build linux,!appengine darwin
+// +build darwin dragonfly freebsd linux,!appengine netbsd openbsd
 
 // Package terminal provides support functions for dealing with terminals, as
 // commonly found on UNIX systems.

ssh/terminal/util_bsd.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin
+// +build darwin dragonfly freebsd netbsd openbsd
 
 package terminal