avformat/movenc: Check that frame_types other than EAC3_FRAME_TYPE_INDEPENDENT have a supported substream id

Fixes: out of array access
Fixes: ffmpeg_bof_1.avi

Found-by: Thuan Pham, Marcel Böhme, Andrew Santosa and Alexandru Razvan Caciulescu with AFLSmart
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/movenc.c

@@ -437,6 +437,12 @@ static int handle_eac3(MOVMuxContext *mov, AVPacket *pkt, MOVTrack *track)
                 info->ec3_done = 1;
                 goto concatenate;
             }
+        } else {
+            if (hdr->substreamid != 0) {
+                avpriv_request_sample(mov->fc, "Multiple non EAC3 independent substreams");
+                ret = AVERROR_PATCHWELCOME;
+                goto end;
+            }
         }
 
         /* fill the info needed for the "dec3" atom */