gst-libs/gst/video/video.*: API: add GST_VIDEO_FORMAT_Y41B and GST_VIDEO_FORMAT_Y42B.

gst-libs/gst/video/video.*: API: add GST_VIDEO_FORMAT_Y41B and GST_VIDEO_FORMAT_Y42B.

Original commit message from CVS:
* gst-libs/gst/video/video.c: (gst_video_calculate_display_ratio),
(gst_video_format_from_fourcc), (gst_video_format_to_fourcc),
(gst_video_format_is_rgb), (gst_video_format_is_yuv),
(gst_video_format_has_alpha), (gst_video_format_get_row_stride),
(gst_video_format_get_pixel_stride),
(gst_video_format_get_component_width),
(gst_video_format_get_component_height),
(gst_video_format_get_component_offset), (gst_video_format_get_size):
* gst-libs/gst/video/video.h: (GST_VIDEO_FORMAT_Y41B),
(GST_VIDEO_FORMAT_Y42B):
API: add GST_VIDEO_FORMAT_Y41B and GST_VIDEO_FORMAT_Y42B.