honor restart interval in mjpeg, fix #861, SpectralFan.mov still decodes correctly

Originally committed as revision 18937 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mjpegdec.c

@@ -827,9 +827,8 @@ static int mjpeg_decode_scan(MJpegDecodeContext *s, int nb_components, int Ah, i
                     }
                 }
             }
-            /* (< 1350) buggy workaround for Spectralfan.mov, should be fixed */
+
-            if (s->restart_interval && (s->restart_interval < 1350) &&
+            if (s->restart_interval && !--s->restart_count) {
-                !--s->restart_count) {
                 align_get_bits(&s->gb);
                 skip_bits(&s->gb, 16); /* skip RSTn */
                 for (i=0; i<nb_components; i++) /* reset dc */