fix multiple inclusion protection for dynvector.hh

[[Imported from SVN: r6131]]

dune/common/dynvector.hh

 // -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 // vi: set et ts=4 sw=2 sts=2:
 // $Id: fvector.hh 6105 2010-08-25 16:06:36Z christi $
-#ifndef DUNE_FVECTOR_HH
-#define DUNE_FVECTOR_HH
+#ifndef DUNE_DYNVECTOR_HH
+#define DUNE_DYNVECTOR_HH
 
 #include <cmath>
 #include <cstddef>