Set AVSTREAM_PARSE_HEADERS flag for AV1 MP4 streams

It help initialize chroma format and other info properly
Chroma format wasn't correct if I use below code:
        avformat_find_stream_info(fmtc, NULL);
        iVideoStream = av_find_best_stream(fmtc, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);
        eChromaFormat = (AVPixelFormat)fmtc->streams[iVideoStream]->codecpar->format;

Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/mov.c

@@ -2423,6 +2423,9 @@ static int mov_finalize_stsd_codec(MOVContext *c, AVIOContext *pb,
     case AV_CODEC_ID_VP9:
         st->need_parsing = AVSTREAM_PARSE_FULL;
         break;
+    case AV_CODEC_ID_AV1:
+        st->need_parsing = AVSTREAM_PARSE_HEADERS;
+        break;
     default:
         break;
     }