gst/wavparse/gstwavparse.c: Missing variable initialization. Add handling of DVI...

gst/wavparse/gstwavparse.c: Missing variable initialization. Add handling of DVI ADPCM. Fix mis-parsing of LIST chunk...

Original commit message from CVS:
* gst/wavparse/gstwavparse.c: (gst_wavparse_create_sourcepad),
(gst_wavparse_parse_fmt), (gst_wavparse_handle_sink_event),
(gst_wavparse_loop):
Missing variable initialization. Add handling of DVI ADPCM. Fix
mis-parsing of LIST chunks. This works around a bug where we mis-
parse non-aligning LIST chunks (so LIST chunks where the contents
don't align with the actual LIST size). The correct fix is to use
rifflib, I'm not going to fix wavparse - too much work. All this
fixes #104878.