Change to fourcc to enable decoding of ffmpeg files.

Change-Id: Ia16f167d904d53bc38cb3a8c841c6c52daad500f
(cherry picked from commit 296421d84c)
reverts: dbd050c vpxdec: correct VP[89] fourccs

vpxdec.c

@@ -49,8 +49,8 @@
 
 static const char *exec_name;
 
-#define VP8_FOURCC (0x30385056)
+#define VP8_FOURCC (0x00385056)
-#define VP9_FOURCC (0x30395056)
+#define VP9_FOURCC (0x00395056)
 static const struct {
   char const *name;
   const vpx_codec_iface_t *(*iface)(void);