avformat/aaxdec: Check for empty segments

Fixes: Timeout
Fixes: 48154/clusterfuzz-testcase-minimized-ffmpeg_dem_AAX_fuzzer-5149094353436672

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

libavformat/aaxdec.c

@@ -250,6 +250,8 @@ static int aax_read_header(AVFormatContext *s)
 
                 start = avio_rb32(pb);
                 size  = avio_rb32(pb);
+                if (!size)
+                    return AVERROR_INVALIDDATA;
                 a->segments[r].start = start + a->data_offset;
                 a->segments[r].end   = a->segments[r].start + size;
                 if (r &&