drop using statement for perf_depth_

rather qualify member variable with this->

opm/simulators/wells/MultisegmentWell.hpp

@@ -180,7 +180,6 @@ namespace Opm
         // multi-phase flow model
         WellSegments::MultiPhaseModel multiphaseModel() const;
 
-        using Base::perf_depth_;
         using Base::num_components_;
         using Base::connectionRates_;
         using Base::ipr_a_;

opm/simulators/wells/MultisegmentWell_impl.hpp

@@ -103,7 +103,7 @@ namespace Opm
         // calcuate the depth difference between the perforations and the perforated grid block
         for (int perf = 0; perf < this->number_of_perforations_; ++perf) {
             const int cell_idx = this->well_cells_[perf];
-            this->cell_perforation_depth_diffs_[perf] = depth_arg[cell_idx] - perf_depth_[perf];
+            this->cell_perforation_depth_diffs_[perf] = depth_arg[cell_idx] - this->perf_depth_[perf];
         }
     }