corrected warnings when compiling with -Wall -W

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@15430 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/mac/pen.h

@@ -30,6 +30,8 @@ public:
     wxPenRefData(const wxPenRefData& data);
     ~wxPenRefData();
 
+    wxPenRefData& operator=(const wxPenRefData& data);
+
 protected:
   int           m_width;
   int           m_style;
@@ -54,7 +56,9 @@ public:
   wxPen();
   wxPen(const wxColour& col, int width, int style);
   wxPen(const wxBitmap& stipple, int width);
-  inline wxPen(const wxPen& pen) { Ref(pen); }
+  wxPen(const wxPen& pen)
+      : wxGDIObject()
+      { Ref(pen); }
   ~wxPen();
 
   inline wxPen& operator = (const wxPen& pen) { if (*this == pen) return (*this); Ref(pen); return *this; }