mpegtsenc: Add an AVClass pointer to the private data

Since a private class is set for this muxer, the callers will
assume that the private data starts with an AVClass pointer.
If no such member exists, the first few bytes of the struct
will be overwritten, and the class pointer may be broken at
any later time.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/mpegtsenc.c

@@ -53,6 +53,7 @@ typedef struct MpegTSService {
 } MpegTSService;
 
 typedef struct MpegTSWrite {
+    const AVClass *av_class;
     MpegTSSection pat; /* MPEG2 pat table */
     MpegTSSection sdt; /* MPEG2 sdt table context */
     MpegTSService **services;