avformat/utils: Do not init parser if probing is unfinished

Fixes assertion failure
Fixes: 136f8b8d47af7892306625e597dee655/signal_sigabrt_7ffff6ae7cc9_8941_ab11bea57c84796418f481f873dc31ba.dvr_ms

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/utils.c

@@ -3139,7 +3139,7 @@ int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
                 st->codec->time_base = st->time_base;
         }
         // only for the split stuff
-        if (!st->parser && !(ic->flags & AVFMT_FLAG_NOPARSE)) {
+        if (!st->parser && !(ic->flags & AVFMT_FLAG_NOPARSE) && st->request_probe <= 0) {
             st->parser = av_parser_init(st->codec->codec_id);
             if (st->parser) {
                 if (st->need_parsing == AVSTREAM_PARSE_HEADERS) {