avformat/mov: Check for EOF in mov_read_iloc()

Fixes: Timeout
Fixes: 49216/clusterfuzz-testcase-minimized-ffmpeg_IO_DEMUXER_fuzzer-6563000529584128

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

libavformat/mov.c

@@ -7555,6 +7555,8 @@ static int mov_read_iloc(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
     for (int i = 0; i < item_count; i++) {
         int item_id = (version < 2) ? avio_rb16(pb) : avio_rb32(pb);
+        if (avio_feof(pb))
+            return AVERROR_INVALIDDATA;
         if (version > 0)
             avio_rb16(pb);  // construction_method.
         avio_rb16(pb);  // data_reference_index.