Don't show advanced subtitle options within the ffmpeg -h generic

advanced options.

Originally committed as revision 13779 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffmpeg.c

@@ -3420,7 +3420,7 @@ static void show_help(void)
                       OPT_GRAB,
                       OPT_GRAB);
     show_help_options(options, "\nAdvanced options:\n",
-                      OPT_EXPERT | OPT_AUDIO | OPT_VIDEO | OPT_GRAB,
+                      OPT_EXPERT | OPT_AUDIO | OPT_VIDEO | OPT_SUBTITLE | OPT_GRAB,
                       OPT_EXPERT);
     printf("\n");
     av_opt_show(avctx_opts[0], NULL);