Fix whitespaces in ProjectedBlockGS

There were still some spurious whitespaces left from d49b1348.

dune/solvers/iterationsteps/projectedblockgsstep.cc

@@ -6,7 +6,7 @@ inline
 void ProjectedBlockGSStep<MatrixType, VectorType>::iterate()
 {
     assert(hasObstacle_!=nullptr);
-	
+
     if (hasObstacle_->size()!= (unsigned int)this->x_->size())
         DUNE_THROW(SolverError, "Size of hasObstacle (" << hasObstacle_->size()
                    << ") doesn't match solution vector (" << this->x_->size() << ")");
@@ -49,7 +49,7 @@ void ProjectedBlockGSStep<MatrixType, VectorType>::iterate()
             // Solve the local constraint minimization problem
             // We use a projected Gauss-Seidel, for lack of anything better
             assert(obstacles_!=nullptr);
-            
+
             Obstacle defectObstacle = (*obstacles_)[i];
             defectObstacle -= x;