@param pb The packbuilder object
@param progress_cb Function to call with progress information during
pack building. Be aware that this is called inline with pack building
operations, so performance may be affected.
@param progress_cb_payload Payload for progress callback.
@return 0 or an error code
Set the callbacks for a packbuilder
@param pb The packbuilder object @param progress_cb Function to call with progress information during pack building. Be aware that this is called inline with pack building operations, so performance may be affected. @param progress_cb_payload Payload for progress callback. @return 0 or an error code