avcodec/jpeg2000dec: non zero image offsets are not supported

Fixes out of array accesses
Fixes Ticket3080
Found-by: ami_stuff
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/jpeg2000dec.c

@@ -243,6 +243,11 @@ static int get_siz(Jpeg2000DecoderContext *s)
     s->tile_offset_y  = bytestream2_get_be32u(&s->g); // YT0Siz
     ncomponents       = bytestream2_get_be16u(&s->g); // CSiz
 
+    if (s->image_offset_x || s->image_offset_y) {
+        avpriv_request_sample(s->avctx, "Support for image offsets");
+        return AVERROR_PATCHWELCOME;
+    }
+
     if (ncomponents <= 0) {
         av_log(s->avctx, AV_LOG_ERROR, "Invalid number of components: %d\n",
                s->ncomponents);