make compile again

dune/solvers/solvers/trustregionsolver.cc

@@ -53,7 +53,7 @@ void TrustRegionSolver<ProblemType,VectorType,MatrixType>::solve()
         VectorType gradient = problem_->f_;
         for (size_t j=0; j<gradient.size(); j++)
             for (int k=0; k<gradient[j].size(); k++)
-                if (mgStep.ignore()[j][k])
+                if (mgStep->ignore()[j][k])
                     gradient[j][k] = 0;
 
         if (this->verbosity_ == Solver::FULL)