avcodec/mjpegdec Fix potential memleak of stereo3D at the end in case of decoding failure

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mjpegdec.c

@@ -2091,6 +2091,7 @@ av_cold int ff_mjpeg_decode_end(AVCodecContext *avctx)
         av_frame_unref(s->picture_ptr);
 
     av_free(s->buffer);
+    av_freep(&s->stereo3d);
     av_freep(&s->ljpeg_buffer);
     s->ljpeg_buffer_size = 0;