Convert to and from YV12 (fixes #156379)

Original commit message from CVS:
Convert to and from YV12 (fixes #156379)

ChangeLog

+2005-02-12  Tim-Philipp Müller  <tim at centricular dot net>
+
+	* gst/ffmpegcolorspace/avcodec.h:
+	* gst/ffmpegcolorspace/gstffmpegcodecmap.c:
+	(gst_ffmpeg_pixfmt_to_caps), (gst_ffmpeg_caps_to_pixfmt),
+	(gst_ffmpegcsp_avpicture_fill):
+	* gst/ffmpegcolorspace/imgconvert.c:
+	  Convert to and from YV12 (fixes #156379).
+
 2005-02-12  Julien MOUTTE  <julien@moutte.net>
 
 	* sys/ximage/ximagesink.c: (gst_ximagesink_xwindow_new),