Add FL/platform.H for compatibility with FLTK 1.4.0 and higher.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@12861 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

CHANGES

@@ -3,6 +3,8 @@ CHANGES IN FLTK 1.3.5					RELEASED: ??? ?? 2017
 
 Bug fixes and other improvements
 
+	- Add FL/platform.H for compatibility with FLTK 1.4 and higher.
+	  This file replaces FL/x.H in FLTK 1.4.0.
 	- Fix Fl_Text_Editor overstrike mode (STR #3463).
 	- More consistent and optimized "gleam" scheme box drawing.
 	- Fix a MinGW build error with new MinGW versions as of Feb 2018

FL/platform.H

@@ -0,0 +1,31 @@
+//
+// "$Id$"
+//
+// Platform abstraction header file for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 1998-2018 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     http://www.fltk.org/COPYING.php
+//
+// Please report all bugs and problems on the following page:
+//
+//     http://www.fltk.org/str.php
+//
+
+// This file is present for compatibility with FLTK 1.4 and later.
+
+// In FLTK 1.4 FL/platform.H replaces FL/x.H.  FLTK 1.4 code that
+// includes FL/platform.H instead of FL/x.H can now be compiled with
+// FLTK 1.3.5 and later versions.
+
+#if !defined(Fl_X_H)
+#include <FL/x.H>
+#endif
+
+//
+// End of "$Id$".
+//