Tests: removed another empty file I missed in c93aebb1de

Its contents were also removed when SDL 1.2 was dropped.

source_lists/boost_unit_tests

@@ -1,7 +1,6 @@
 tests/gui/fire_event.cpp
 tests/gui/iterator.cpp
 tests/gui/test_gui2.cpp
-tests/gui/test_save_dialog.cpp
 tests/gui/visitor.cpp
 tests/main.cpp
 tests/test_addons.cpp

src/tests/gui/test_save_dialog.cpp

@@ -1,34 +0,0 @@
-/*
-   Copyright (C) 2008 - 2017 by Pauli Nieminen <paniemin@cc.hut.fi>
-   Part of the Battle for Wesnoth Project http://www.wesnoth.org/
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2 of the License, or
-   (at your option) any later version.
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY.
-
-   See the COPYING file for more details.
-*/
-
-#define GETTEXT_DOMAIN "wesnoth-test"
-
-#include <boost/test/unit_test.hpp>
-
-#include <boost/test/unit_test_suite.hpp>
-
-
-#include "key.hpp"
-#include "filesystem.hpp"
-#include "savegame.hpp"
-#include "units/types.hpp"
-
-#include <SDL.h>
-
-#include "tests/utils/fake_display.hpp"
-#include "tests/utils/auto_parameterized.hpp"
-
-
-// Linker workarounds end here
-