avformat/asfdec_f: Saturate presentation time in marker

Fixes: signed integer overflow: -9223372036315799520 - 3873890816 cannot be represented in type 'long'
Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5009302746431488

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit cedb4736f5)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/asfdec_f.c

@@ -670,7 +670,7 @@ static int asf_read_marker(AVFormatContext *s)
 
         avio_rl64(pb);             // offset, 8 bytes
         pres_time = avio_rl64(pb); // presentation time
-        pres_time -= asf->hdr.preroll * 10000;
+        pres_time = av_sat_sub64(pres_time, asf->hdr.preroll * 10000);
         avio_rl16(pb);             // entry length
         avio_rl32(pb);             // send time
         avio_rl32(pb);             // flags