Original commit message from CVS:
* gst/qtdemux/qtdemux.c: (gst_qtdemux_get_src_formats),
(gst_qtdemux_src_convert), (gst_qtdemux_get_src_query_types),
(gst_qtdemux_get_event_mask), (gst_qtdemux_handle_src_query),
(gst_qtdemux_handle_src_event), (gst_qtdemux_add_stream):
Add prototype code for handling seeking and querying.