closed gop support & flags2 as all bits in flags are used

and a few minor things i forgot to commit ...

Originally committed as revision 2718 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mjpeg.c

@@ -855,7 +855,6 @@ static int mjpeg_decode_init(AVCodecContext *avctx)
 
     /* ugly way to get the idct & scantable FIXME */
     memset(&s2, 0, sizeof(MpegEncContext));
-    s2.flags= avctx->flags;
     s2.avctx= avctx;
 //    s2->out_format = FMT_MJPEG;
     s2.width = 8;