and return it on the subsequent read call (unless no data has been read, in
which case return it on this call as before). This ensures that when the
user returns OGGZ_STOP_OK or OGGZ_STOP_ERR in a read callback, that condition
is acknowledged in a subsequent call to oggz_read_*().
git-svn-id: http://svn.annodex.net/liboggz/trunk@2012 8158c8cd-e7e1-0310-9fa4-c5954c97daef