Avcodec: prepare the binding to VP8 in ffmpeg

(cherry picked from commit 0e70f9ed44c34c7ba22dcf11bc2b1e04c3bb9374)
(cherry picked from commit 488fd4bd13150d12327a67fa203b406dcd03a0c7)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/codec/avcodec/fourcc.c

@@ -204,6 +204,10 @@ static const struct
     { VLC_CODEC_INDEO5, CODEC_ID_INDEO5, VIDEO_ES },
 #endif
 
+#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT( 52, 68, 2 )
+    { VLC_CODEC_VP8, CODEC_ID_VP8, VIDEO_ES },
+#endif
+
     /* Videogames Codecs */
 
     { VLC_CODEC_INTERPLAY, CODEC_ID_INTERPLAY_VIDEO, VIDEO_ES },