vendor: update buildkit to f238f1e

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/golang.org/x/crypto/ssh/agent/server.go

@@ -541,6 +541,9 @@ func ServeAgent(agent Agent, c io.ReadWriter) error {
 			return err
 		}
 		l := binary.BigEndian.Uint32(length[:])
+		if l == 0 {
+			return fmt.Errorf("agent: request size is 0")
+		}
 		if l > maxAgentResponseBytes {
 			// We also cap requests.
 			return fmt.Errorf("agent: request too large: %d", l)

vendor/golang.org/x/crypto/ssh/terminal/util_windows.go

@@ -64,13 +64,15 @@ func Restore(fd int, state *State) error {
 	return windows.SetConsoleMode(windows.Handle(fd), state.mode)
 }
 
-// GetSize returns the dimensions of the given terminal.
+// GetSize returns the visible dimensions of the given terminal.
+//
+// These dimensions don't include any scrollback buffer height.
 func GetSize(fd int) (width, height int, err error) {
 	var info windows.ConsoleScreenBufferInfo
 	if err := windows.GetConsoleScreenBufferInfo(windows.Handle(fd), &info); err != nil {
 		return 0, 0, err
 	}
-	return int(info.Size.X), int(info.Size.Y), nil
+	return int(info.Window.Right - info.Window.Left + 1), int(info.Window.Bottom - info.Window.Top + 1), nil
 }
 
 // ReadPassword reads a line of input from a terminal without local echo.  This