Update xvid plugin to latest xvid (1.0.0-beta3) API.

Update xvid plugin to latest xvid (1.0.0-beta3) API.

Original commit message from CVS:
2004-01-03  Ronald Bultje  <rbultje@ronald.bitfreak.net>

reviewed by: <delete if not using a buddy>

* configure.ac:
* ext/xvid/gstxvid.c: (gst_xvid_init), (gst_xvid_error),
(gst_xvid_structure_to_csp), (gst_xvid_csp_to_caps):
* ext/xvid/gstxvid.h:
* ext/xvid/gstxviddec.c: (gst_xviddec_class_init),
(gst_xviddec_init), (gst_xviddec_setup), (gst_xviddec_chain),
(gst_xviddec_src_link), (gst_xviddec_sink_link),
(gst_xviddec_change_state):
* ext/xvid/gstxviddec.h:
* ext/xvid/gstxvidenc.c: (gst_xvidenc_profile_get_type),
(gst_xvidenc_base_init), (gst_xvidenc_class_init),
(gst_xvidenc_init), (gst_xvidenc_setup), (gst_xvidenc_chain),
(gst_xvidenc_link), (gst_xvidenc_set_property),
(gst_xvidenc_get_property), (gst_xvidenc_change_state):
* ext/xvid/gstxvidenc.h:
Update xvid plugin to latest xvid (1.0.0-beta3) API.