Remove the virtual destructor of class Fl_X that is no longer needed.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3-porting@11625 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/mac.H

@@ -123,7 +123,6 @@ extern NSCursor *fl_default_cursor;
 // WARNING: this object is highly subject to change!
 class Fl_X {
 public:
-  virtual ~Fl_X() {}       // very important
   Window xid;              // pointer to the Cocoa window object (FLWindow*)
   Fl_Offscreen other_xid;  // pointer for offscreen bitmaps (overlay window)
   Fl_Window *w;            // FLTK window for 

FL/win32.H

@@ -49,7 +49,6 @@ typedef HWND Window;
 // Warning: this object is highly subject to change!
 class FL_EXPORT Fl_X {
 public:
-  virtual ~Fl_X() {}       // very important
   // member variables - add new variables only at the end of this block
   Window xid;
   HBITMAP other_xid; // for double-buffered windows

FL/x.H

@@ -114,7 +114,6 @@ extern FL_EXPORT Fl_XFont_On_Demand fl_xfont;
 // FL_LIBRARY or FL_INTERNALS must be defined to access this class.
 class FL_EXPORT Fl_X {
 public:
-  virtual ~Fl_X() {}       // very important
   Window xid;
   Window other_xid;
   Fl_Window *w;