gst/avi/gstavidemux.c: Add some debugging. Better detection of broken indexes and the accompanying index recovery. No...

Original commit message from CVS:
* gst/avi/gstavidemux.c: (gst_avi_demux_stream_index),
(gst_avi_demux_stream_scan), (gst_avi_demux_handle_seek),
(gst_avi_demux_process_next_entry):
Add some debugging. Better detection of broken indexes and the
accompanying index recovery. No infinite loops on state changes
when we're still in our loopfunction.