Original commit message from CVS:
* ext/theora/theoradec.c: (_inc_granulepos),
(theora_dec_sink_event), (theora_handle_comment_packet),
(theora_handle_type_packet), (theora_handle_header_packet),
(theora_handle_data_packet), (theora_dec_chain),
(theora_dec_change_state):
Refactor a bit, use STREAM_LOCK.