GUI2: set restore flag on a few more dialogs

src/gui/dialogs/game_delete.cpp

@@ -60,6 +60,8 @@ static void set_dont_ask_again(const bool ask_again)
 
 tgame_delete::tgame_delete()
 {
+	set_restore(true);
+
 	register_bool(
 			"dont_ask_again", true, &get_dont_ask_again, &set_dont_ask_again);
 }

src/gui/dialogs/game_save.cpp

@@ -61,6 +61,8 @@ tgame_save_message::tgame_save_message(std::string& filename,
 									   const std::string& title,
 									   const std::string& message)
 {
+	set_restore(true);
+
 	register_label("lblTitle", true, title);
 	register_text("txtFilename", false, filename, true);
 	register_label("lblMessage", true, message);

src/gui/dialogs/mp_host_game_prompt.cpp

@@ -57,6 +57,8 @@ static void set_do_not_show_again(const bool do_not_show_again)
 
 tmp_host_game_prompt::tmp_host_game_prompt()
 {
+	set_restore(true);
+
 	register_bool("do_not_show_again",
 				  true,
 				  &get_do_not_show_again,