fix emacs layout hints

dune/istl/operators.hh

 // SPDX-FileCopyrightText: Copyright © DUNE Project contributors, see file LICENSE.md in module root
 // SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
-// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 // vi: set et ts=4 sw=2 sts=2:
 #ifndef DUNE_ISTL_OPERATORS_HH
 #define DUNE_ISTL_OPERATORS_HH
@@ -180,3 +179,10 @@ namespace Dune {
 } // end namespace
 
 #endif
+
+// Emacs configuration
+// Local Variables:
+// tab-width: 4
+// indent-tabs-mode: nil
+// c-basic-offset: 2
+// End: