jp2_output_box::set_rubber_length

Signals to the box that it can flush any buffered data and pass all future body bytes directly to the output from now on. This call is legal only when the box is already open. The box will have a zero-valued length field and must be the last box in the data stream. This function is generally invoked whenever a sub-box is created with rubber length or is assigned rubber length by one of its own sub-boxes.