Add some WXDLLIMPEXP's

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@24079 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/utils.cpp

@@ -1244,7 +1244,7 @@ extern long wxCharsetToCodepage(const wxChar *name)
   NULL. classname is the desired wndclass classname. If function succesfully
   registers the class, pclassname will be set to classname.
  */
-extern "C" HWND
+extern "C" WXDLLIMPEXP_BASE HWND
 wxCreateHiddenWindow(LPCTSTR *pclassname, LPCTSTR classname, WNDPROC wndproc)
 {
     wxCHECK_MSG( classname && pclassname && wndproc, NULL,