Fix Ok/IsOk() mess in wxGDIObject-derived classes; also added

wxGDIObject::Create/CloneGDIRefData() and implemented them for (almost) all
ports


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@50727 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/cocoa/colour.h

@@ -50,7 +50,7 @@ public:
     virtual ~wxColour();
 
     // accessors
-    bool IsOk() const { return m_cocoaNSColor; }
+    virtual bool IsOk() const { return m_cocoaNSColor; }
     WX_NSColor GetNSColor() { return m_cocoaNSColor; }
 
     unsigned char Red() const { return m_red; }