Re-add print dialog access to macOS.

Ability to bring up the print dialog from the macOS build was removed in
Tux Paint 0.9.23 to support the new build mechanism.  It has been re-added.
To access it, option-click the print icon, or configure Tux Paint to always
bring up the dialog upon print.

src/macos_print.h

@@ -0,0 +1,40 @@
+//
+//  macosx_print.h
+//  Tux Paint
+//
+//  Created by Darrell Walisser on Sat Mar 15 2003.
+//  Modified by Martin Fuhrer 2007.
+//  Copyright (c) 2007 Darrell Walisser, Martin Fuhrer. All rights reserved.
+//  $Id$
+//
+//  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; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program; if not, write to the Free Software
+//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//  (See COPYING.txt)
+//
+
+#include "SDL.h"
+
+const char *SurfacePrint(SDL_Surface * surface, int showDialog);
+int DisplayPageSetup(const SDL_Surface * surface);
+
+#ifdef OBJECTIVEC
+
+@interface PrintSheetController:NSObject
+{
+  bool displayPrintSetupSheet;
+  bool displayPrintSheet;
+}
+
+-@end
+#endif  /* OBJECTIVEC */