Delegate wxGraphicsBitmap::ConvertToImage to the renderer so we do not end up with more than one definition of the method when building with both the GDI+ GC and the Cairo GC enabled at the same time.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69485 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/graphics.h

@@ -969,6 +969,13 @@ public:
      */
     virtual wxGraphicsBitmap CreateBitmapFromImage(const wxImage& image) = 0;
 
+    /**
+       Creates a wxImage from a wxGraphicsBitmap.
+
+       This method is used by the more convenient wxGraphicsBitmap::ConvertToImage.
+    */
+    virtual wxImage CreateImageFromBitmap(const wxGraphicsBitmap& bmp) = 0;
+
     /**
         Creates wxGraphicsBitmap from a native bitmap handle.