use WXDLLIMPEXP_FWD_CORE instead of WXDLLEXPORT

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@49004 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/dialup.cpp

@@ -163,7 +163,7 @@ struct WXDLLEXPORT wxRasThreadData
     HANDLE  hEventRas,  // automatic event which RAS signals when status changes
             hEventQuit; // manual event which we signal when we terminate
 
-    class WXDLLEXPORT wxDialUpManagerMSW *dialUpManager;  // the owner
+    class WXDLLIMPEXP_FWD_CORE wxDialUpManagerMSW *dialUpManager;  // the owner
 };
 
 // ----------------------------------------------------------------------------