Change to go1.6.1 and vendoring

vendor/github.com/kr/pty/ioctl.go

@@ -0,0 +1,11 @@
+package pty
+
+import "syscall"
+
+func ioctl(fd, cmd, ptr uintptr) error {
+	_, _, e := syscall.Syscall(syscall.SYS_IOCTL, fd, cmd, ptr)
+	if e != 0 {
+		return e
+	}
+	return nil
+}