avcodec/mjpegdec: only run EOI emulation code when there was a scan

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 361e27a3d8)

libavcodec/mjpegdec.c

@@ -1811,7 +1811,7 @@ eoi_parser:
                    (get_bits_count(&s->gb) + 7) / 8, get_bits_count(&s->gb));
         }
     }
-    if (s->got_picture) {
+    if (s->got_picture && s->cur_scan) {
         av_log(avctx, AV_LOG_WARNING, "EOI missing, emulating\n");
         goto eoi_parser;
     }