avcodec/h264data: Add missing rational.h inclusion

Fixes checkheaders.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/h264data.h

@@ -21,6 +21,7 @@
 
 #include <stdint.h>
 
+#include "libavutil/rational.h"
 #include "h264.h"
 
 extern const uint8_t ff_h264_golomb_to_pict_type[5];