gst/avi/gstavidemux.c: No need to take the STREAM_LOCK in the loop function. Improve some debug messages. Don't leak ...

Original commit message from CVS:
* gst/avi/gstavidemux.c: (gst_avi_demux_parse_stream),
(gst_avi_demux_process_next_entry), (gst_avi_demux_stream_data),
(gst_avi_demux_loop):
No need to take the STREAM_LOCK in the loop function. Improve
some debug messages. Don't leak pad names in debug messages.