func detectDirDiff(upper, lower string) *diffDirOptions {
	return nil
}
detectDirDiff returns diff dir options if a directory could
be found in the mount info for upper which is the direct
diff with the provided lower directory
package fs
import (
	"bytes"
	"os"
	"syscall"
	"github.com/containerd/continuity/sysx"
	"github.com/pkg/errors"
)