Remove all trailing spaces

No real changes, just clean up sources by removing trailing spaces from
all the non-generated files.

This should hopefully avoid future commits mixing significant changes
with insignificant whitespace ones.

include/wx/osx/popupwin.h

@@ -27,7 +27,7 @@ public:
     bool Create(wxWindow *parent, int flags = wxBORDER_NONE);
 
     virtual bool Show(bool show = true);
-    
+
     wxDECLARE_DYNAMIC_CLASS_NO_COPY(wxPopupWindow);
 };