Fixes for GST_FOURCC_FORMAT API change.

Fixes for GST_FOURCC_FORMAT API change.

Original commit message from CVS:
* gst-libs/gst/riff/riff-media.c: (gst_riff_create_video_caps),
(gst_riff_create_iavs_caps):
* gst-libs/gst/riff/riff-read.c: (gst_riff_parse_file_header),
(gst_riff_parse_strh), (gst_riff_parse_strf_vids),
(gst_riff_parse_info):
* gst/videotestsrc/videotestsrc.c: (paintinfo_find_by_structure):
* sys/v4l/gstv4lsrc.c: (gst_v4lsrc_set_caps):
* sys/xvimage/xvimagesink.c: (gst_xvimagesink_setcaps):
Fixes for GST_FOURCC_FORMAT API change.