avformat/mov: Fix MSAN issue with stsd_id

Fixes: use of uninitialized value
Fixes: bbb-320x240-2video-2audio.mp4

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/mov.c

@@ -1472,6 +1472,7 @@ static int update_frag_index(MOVContext *c, int64_t offset)
         frag_stream_info[i].index_base = -1;
         frag_stream_info[i].index_entry = -1;
         frag_stream_info[i].encryption_index = NULL;
+        frag_stream_info[i].stsd_id = -1;
     }
 
     if (index < c->frag_index.nb_items)