use DECLARE_NO_COPY_CLASS() where applicable (patch 633384)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@18525 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/snglinst.h

@@ -60,6 +60,8 @@ private:
 
     // the implementation details (platform specific)
     class WXDLLEXPORT wxSingleInstanceCheckerImpl *m_impl;
+
+    DECLARE_NO_COPY_CLASS(wxSingleInstanceChecker)
 };
 
 #endif // wxUSE_SNGLINST_CHECKER