Add missing implementation of convergence tester destructor

src/convergence_tester.cpp

@@ -0,0 +1,27 @@
+// ====================================================================
+// This file is part of FlexibleSUSY.
+//
+// FlexibleSUSY is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published
+// by the Free Software Foundation, either version 3 of the License,
+// or (at your option) any later version.
+//
+// FlexibleSUSY is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with FlexibleSUSY.  If not, see
+// <http://www.gnu.org/licenses/>.
+// ====================================================================
+
+#include "convergence_tester.hpp"
+
+namespace flexiblesusy {
+
+Convergence_tester::~Convergence_tester()
+{
+}
+
+} // namespace flexiblesusy