fixed linking with visibility enable on Ubuntu and some other systems (any gcc 4.2 amd64?) by removing superfluous virtual wxColour::Ok() (already in wxColourBase)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47846 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/colour.h

@@ -27,7 +27,6 @@ public:
 
     virtual ~wxColour();
 
-    bool Ok() const { return IsOk(); }
     bool IsOk() const { return m_refData != NULL; }
 
     bool operator == ( const wxColour& col ) const;