Fix wxDataViewCtrl::GetMainWindow() signature on OS X.

Return wxWindow* as other ports do, not wxControl*.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70339 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/osx/dataview.h

@@ -150,7 +150,7 @@ public:
               const wxValidator& validator = wxDefaultValidator,
               const wxString& name = wxDataViewCtrlNameStr);
 
-  virtual wxControl* GetMainWindow() // not used for the native implementation
+  virtual wxWindow* GetMainWindow() // not used for the native implementation
   {
     return this;
   }