include the headers needed for its compilation from the header itself

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@53025 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/private/datecontrols.h

@@ -11,6 +11,10 @@
 #ifndef _MSW_PRIVATE_DATECONTROLS_H_
 #define _MSW_PRIVATE_DATECONTROLS_H_
 
+#include "wx/datetime.h"
+
+#include "wx/msw/wrapwin.h"
+
 // namespace for the helper functions related to the date controls
 namespace wxMSWDateControls
 {