oggdec: Take internal state into account.

oggdec: Take internal state into account.

It is incorrect to look only at the node status of the oggdec buffer
tree node and do nothing if the status is zero. In case the previous
call to ogg_post_select() returned early because it hit the maximal
output buffer size limit, the node status is zero if there is no more
input available, but ov_read() will nevertheless return data which
should be fed to the children of the decoder node as soon as possible.

Fix this by remembering whether we hit the limit.