When using a recent liboggz, liboggplay fails to play some files. It
appears it's only files with Kate streams, however some files with
Kate streams do play fine, but liboggplay reports unknown
category/language, so that's probably still failing, but in a way that
liboggplay can recover from.

A sample file which worked before and does not work now is the good old:
http://people.xiph.org/~oggk/Stephen_Fry-Happy_Birthday_GNU-hq_600px_780kbit.ogv


This file is seen as correct by oggz-validate.

Issue:

* when oggz_read() sees the first few packets before it sees a
granulepos, it buffers them in a dlist
* then, oggz_read_deliver_packet() is a dlist callback which goes
through these buffered packets and calls the read callback for each
* the commit you found by bisection returns an error if the
read_callback returns non-zero; previously the read_callback return
values were ignored
* liboggplay's read_predetected(), the read_callback in use during
stream detection, returns 1 (OGGZ_STOP_OK) when it has done what it
needs to do

... hence, the STOP_OK value gets turned into an error value by the
bad commit.

Reported-by:  <ogg.k.ogg.k@googlemail.com>
Signed-off-by: Conrad Parker <conrad@metadecks.org>