[ConfigParser] Protect the #include "config.h" by #if HAVE_CONFIG_H

[[Imported from SVN: r6011]]

dune/common/test/configparsertest.cc

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