avformat: Make AVChapter.id an int64_t on next major bump

64 bits are needed in order to retain the uid values of Matroska
chapters; the type is kept signed because the semantics of NUT chapters
depend upon whether the id is > 0 or < 0.

Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/utils.c

@@ -4626,7 +4626,11 @@ AVProgram *av_new_program(AVFormatContext *ac, int id)
     return program;
 }
 
+#if FF_API_CHAPTER_ID_INT
 AVChapter *avpriv_new_chapter(AVFormatContext *s, int id, AVRational time_base,
+#else
+AVChapter *avpriv_new_chapter(AVFormatContext *s, int64_t id, AVRational time_base,
+#endif
                               int64_t start, int64_t end, const char *title)
 {
     AVChapter *chapter = NULL;