cafenc: do not include riff.h

ff_codec_get_tag() was moved to internal.h
Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavformat/cafenc.c

@@ -21,7 +21,6 @@
 
 #include "avformat.h"
 #include "caf.h"
-#include "riff.h"
 #include "isom.h"
 #include "avio_internal.h"
 #include "libavutil/intfloat.h"