updated vendored kr/pty to the current master + Solaris support:

https://github.com/kr/pty/pull/64

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

@@ -8,23 +8,28 @@ import (
 )
 
 func open() (pty, tty *os.File, err error) {
-	p, err := os.OpenFile("/dev/ptmx", os.O_RDWR, 0)
+	pFD, err := syscall.Open("/dev/ptmx", syscall.O_RDWR|syscall.O_CLOEXEC, 0)
 	if err != nil {
 		return nil, nil, err
 	}
+	p := os.NewFile(uintptr(pFD), "/dev/ptmx")
+	// In case of error after this point, make sure we close the ptmx fd.
+	defer func() {
+		if err != nil {
+			_ = p.Close() // Best effort.
+		}
+	}()
 
 	sname, err := ptsname(p)
 	if err != nil {
 		return nil, nil, err
 	}
 
-	err = grantpt(p)
-	if err != nil {
+	if err := grantpt(p); err != nil {
 		return nil, nil, err
 	}
 
-	err = unlockpt(p)
-	if err != nil {
+	if err := unlockpt(p); err != nil {
 		return nil, nil, err
 	}