avformat/mov: return correct value in mov_read_cmov

On some failure paths, the error code is not correctly set.
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/mov.c

@@ -4894,6 +4894,7 @@ static int mov_read_cmov(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     if (ret < 0)
         goto free_and_return;
 
+    ret = AVERROR_INVALIDDATA;
     if (uncompress (moov_data, (uLongf *) &moov_len, (const Bytef *)cmov_data, cmov_len) != Z_OK)
         goto free_and_return;
     if (ffio_init_context(&ctx, moov_data, moov_len, 0, NULL, NULL, NULL, NULL) != 0)