Linux: Fixed a leaking XWindowSystem

modules/juce_gui_basics/native/juce_linux_X11.h

@@ -36,7 +36,7 @@ typedef unsigned long WindowType;
 
 
 //==============================================================================
-class XWindowSystem
+class XWindowSystem :  public DeletedAtShutdown
 {
 public:
     XDisplay displayRef() noexcept;