ffmpeg, ffprobe: don't "merge" side data into packet data by default

Preparation for potentially disabling merged side data by default in the
libs. Do this in particular because it affects fate tests.

The changed tests either reflect added packet side data, or the changed
packet size due to merged side data removal reducing the packet size.

libavformat/tests/seek.c

@@ -67,6 +67,8 @@ int main(int argc, char **argv)
     int frame_count = 1;
     int duration = 4;
 
+    ic->flags |= AVFMT_FLAG_KEEP_SIDE_DATA;
+
     for(i=2; i<argc; i+=2){
         if       (!strcmp(argv[i], "-seekforw")){
             seekfirst = atoi(argv[i+1]);