gst/avi/gstavimux.*: - add odml (large file) index support

gst/avi/gstavimux.*: - add odml (large file) index support

Original commit message from CVS:
Patch by: Mark Nauwelaerts  <manauw at skynet be>
* gst/avi/gstavimux.c: (gst_avi_mux_finalize), (gst_avi_mux_init),
(gst_avi_mux_vidsink_set_caps), (gst_avi_mux_audsink_set_caps),
(gst_avi_mux_write_tag), (gst_avi_mux_riff_get_avi_header),
(gst_avi_mux_riff_get_avix_header), (gst_avi_mux_write_avix_index),
(gst_avi_mux_add_index), (gst_avi_mux_bigfile),
(gst_avi_mux_start_file), (gst_avi_mux_stop_file),
(gst_avi_mux_handle_event), (gst_avi_mux_do_audio_buffer),
(gst_avi_mux_do_video_buffer), (gst_avi_mux_do_one_buffer),
(gst_avi_mux_change_state):
* gst/avi/gstavimux.h:
Some enhancements for avimux (#342526):
- add odml (large file) index support
- store codec init data (e.g. huffyuv)
- miscellaneous other fixes/cleanups