Make wxLog non-copyable

It doesn't make sense to copy objects of this class and this wouldn't
work correctly due to the presence of m_formatter field.

See https://github.com/wxWidgets/wxWidgets/pull/1389

include/wx/log.h

@@ -690,6 +690,8 @@ private:
 #if WXWIN_COMPATIBILITY_2_8
     static wxTraceMask ms_ulTraceMask;   // controls wxLogTrace behaviour
 #endif // WXWIN_COMPATIBILITY_2_8
+
+    wxDECLARE_NO_COPY_CLASS(wxLog);
 };
 
 // ----------------------------------------------------------------------------