Original commit message from CVS:
* gst/qtdemux/qtdemux.c: (gst_qtdemux_init),
(gst_qtdemux_handle_src_query), (gst_qtdemux_change_state),
(next_entry_size), (gst_qtdemux_chain):
* gst/qtdemux/qtdemux.h:
Make push-based work if mdat atom is before moov atom.
Don't answer duration query. This should be transformed into replying
FALSE to seek events.