Change to go1.6.1 and vendoring

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

@@ -0,0 +1,60 @@
+package pty
+
+import (
+	"errors"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+func open() (pty, tty *os.File, err error) {
+	p, err := os.OpenFile("/dev/ptmx", os.O_RDWR, 0)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	sname, err := ptsname(p)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	err = grantpt(p)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	err = unlockpt(p)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	t, err := os.OpenFile(sname, os.O_RDWR, 0)
+	if err != nil {
+		return nil, nil, err
+	}
+	return p, t, nil
+}
+
+func ptsname(f *os.File) (string, error) {
+	n := make([]byte, _IOC_PARM_LEN(syscall.TIOCPTYGNAME))
+
+	err := ioctl(f.Fd(), syscall.TIOCPTYGNAME, uintptr(unsafe.Pointer(&n[0])))
+	if err != nil {
+		return "", err
+	}
+
+	for i, c := range n {
+		if c == 0 {
+			return string(n[:i]), nil
+		}
+	}
+	return "", errors.New("TIOCPTYGNAME string not NUL-terminated")
+}
+
+func grantpt(f *os.File) error {
+	return ioctl(f.Fd(), syscall.TIOCPTYGRANT, 0)
+}
+
+func unlockpt(f *os.File) error {
+	return ioctl(f.Fd(), syscall.TIOCPTYUNLK, 0)
+}