ext/: Remove STREAM locks as they are taken in core now.

ext/: Remove STREAM locks as they are taken in core now.

Original commit message from CVS:
* ext/ogg/gstoggdemux.c: (gst_ogg_pad_dispose),
(gst_ogg_pad_typefind), (gst_ogg_pad_submit_packet),
(gst_ogg_chain_new_stream), (gst_ogg_demux_perform_seek),
(gst_ogg_demux_chain), (gst_ogg_demux_loop),
(gst_ogg_demux_sink_activate):
* ext/theora/theoradec.c: (theora_dec_src_event),
(theora_handle_comment_packet), (theora_dec_chain),
(theora_dec_change_state):
* ext/vorbis/vorbisdec.c: (vorbis_dec_sink_event),
(vorbis_handle_data_packet), (vorbis_dec_chain),
(vorbis_dec_change_state):
Remove STREAM locks as they are taken in core now.
Never set bogus granulepos on vorbis/theora.
Fix leaks in theoradec tag parsing.