Remove trailing whitespace from several files

No real changes.

See https://github.com/wxWidgets/wxWidgets/pull/787

include/wx/xrc/xmlreshandler.h

@@ -407,7 +407,7 @@ protected:
     wxObject* GetInstance() const             { return m_instance; }
     wxWindow* GetParentAsWindow() const       { return m_parentAsWindow; }
 
-    
+
     wxArrayString m_styleNames;
     wxArrayInt m_styleValues;