Fix 'make checkheaders', based on a patch by Diego Pettenò, flameeyes gmail com.

Originally committed as revision 15552 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/internal.h

@@ -21,6 +21,8 @@
 #ifndef AVFORMAT_INTERNAL_H
 #define AVFORMAT_INTERNAL_H
 
+#include <stdint.h>
+
 char *ff_data_to_hex(char *buf, const uint8_t *src, int size);
 
 #endif /* AVFORMAT_INTERNAL_H */