[PL] Delete pointers in destructors.

This removes a memory leak.

ProcessLib/GroundwaterFlowProcess.h

@@ -193,6 +193,9 @@ public:
 
     ~GroundwaterFlowProcess()
     {
+        for (auto p : _neumann_bcs)
+            delete p;
+
         for (auto p : _local_assemblers)
             delete p;
 

ProcessLib/NeumannBc.h

@@ -77,6 +77,11 @@ public:
 
     ~NeumannBc()
     {
+        for (auto p : _all_mesh_subsets)
+            delete p;
+
+        delete _mesh_subset_all_nodes;
+
         for (auto e : _elements)
             delete e;