ssh/terminal: add AIX operating system

This commit adds AIX operation system to ssh/terminal package.

Change-Id: I31ccec5512dbf476eaf22ff79951b5fab434d5fd
Reviewed-on: https://go-review.googlesource.com/c/151077
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
diff --git a/ssh/terminal/util.go b/ssh/terminal/util.go
index 731c89a..9a3fb09 100644
--- a/ssh/terminal/util.go
+++ b/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 darwin dragonfly freebsd linux,!appengine netbsd openbsd
+// +build aix darwin dragonfly freebsd linux,!appengine netbsd openbsd
 
 // Package terminal provides support functions for dealing with terminals, as
 // commonly found on UNIX systems.
diff --git a/ssh/terminal/util_aix.go b/ssh/terminal/util_aix.go
new file mode 100644
index 0000000..dfcd627
--- /dev/null
+++ b/ssh/terminal/util_aix.go
@@ -0,0 +1,12 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build aix
+
+package terminal
+
+import "golang.org/x/sys/unix"
+
+const ioctlReadTermios = unix.TCGETS
+const ioctlWriteTermios = unix.TCSETS