make compile: x_ is a pointer not an object

dune/solvers/iterationsteps/projectedgradientstep.hh

@@ -48,7 +48,7 @@ public:
     //! Perform one iteration
     virtual void iterate() {
         VectorType negativeGradient=*rhs_;
-        mat_->mmv(this->x_,negativeGradient);
+        mat_->mmv(*this->x_,negativeGradient);
         computeGeneralizedCP(negativeGradient);
     }