config.h was not included

dune/common/test/conversiontest.cc

 // -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 // vi: set et ts=4 sw=2 sts=2:
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
 #include <iostream>
 #include <dune/common/typetraits.hh>