kconfig: make use of menu_get_ext_help in gconfig

	GtkTextBuffer *buffer;

	GtkTextIter start, end;

	const char *prompt = _(menu_get_prompt(menu));

	gchar *name;

	const char *help;

	struct gstr help = str_new();

	help = menu_get_help(menu);

	/* Gettextize if the help text not empty */

	if ((help != 0) && (help[0] != 0))

		help = _(help);

	if (menu->sym && menu->sym->name)

		name = g_strdup_printf(menu->sym->name);

	else

		name = g_strdup("");

	menu_get_ext_help(menu, &help);

	buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(text_w));

	gtk_text_buffer_get_bounds(buffer, &start, &end);

	gtk_text_buffer_get_end_iter(buffer, &end);

	gtk_text_buffer_insert_with_tags(buffer, &end, prompt, -1, tag1,

					 NULL);

	gtk_text_buffer_insert_at_cursor(buffer, " ", 1);

	gtk_text_buffer_get_end_iter(buffer, &end);

	gtk_text_buffer_insert_with_tags(buffer, &end, name, -1, tag1,

					 NULL);

	gtk_text_buffer_insert_at_cursor(buffer, "\n\n", 2);

	gtk_text_buffer_get_end_iter(buffer, &end);

	gtk_text_buffer_insert_with_tags(buffer, &end, help, -1, tag2,

	gtk_text_buffer_insert_with_tags(buffer, &end, str_get(&help), -1, tag2,

					 NULL);

	str_free(&help);

}

	} else {

		str_append(help, nohelp_text);

	}

	if (sym)

		get_symbol_str(help, sym);

}