VC6 build fix

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@66990 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/filefn.cpp

@@ -1826,6 +1826,11 @@ int WXDLLEXPORT wxParseCommonDialogsFilter(const wxString& filterStr,
 }
 
 #if defined(__WINDOWS__) && !(defined(__UNIX__) || defined(__OS2__))
+
+#ifndef INVALID_FILE_ATTRIBUTES
+#define INVALID_FILE_ATTRIBUTES     ((DWORD)-1)
+#endif
+
 static bool wxCheckWin32Permission(const wxString& path, DWORD access)
 {
     // quoting the MSDN: "To obtain a handle to a directory, call the