avformat/mov: Check for EOF in mov_read_glbl()

Fixes: Infinite loop
Fixes: 41351/clusterfuzz-testcase-minimized-ffmpeg_dem_MOV_fuzzer-5433895854669824

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

@@ -1930,6 +1930,8 @@ static int mov_read_glbl(MOVContext *c, AVIOContext *pb, MOVAtom atom)
         // wrap a whole fiel atom inside of a glbl atom.
         unsigned size = avio_rb32(pb);
         unsigned type = avio_rl32(pb);
+        if (avio_feof(pb))
+            return AVERROR_INVALIDDATA;
         avio_seek(pb, -8, SEEK_CUR);
         if (type == MKTAG('f','i','e','l') && size == atom.size)
             return mov_read_default(c, pb, atom);