Merge pull request #742 from GitPaean/fixing_running_with_dune2.6

return proper communicator for DUNE2.6 (<2.7)

opm/models/nonlinear/newtonmethod.hh

@@ -155,19 +155,6 @@ struct NewtonMaxIterations<TypeTag, TTag::NewtonMethod> { static constexpr int v
 } // namespace Opm::Properties
 
 namespace Opm {
-namespace detail
-{
-inline auto getMPIHelperCommunicator()
-{
-#if DUNE_VERSION_NEWER(DUNE_COMMON, 2, 7)
-    return Dune::MPIHelper::getCommunicator();
-#else
-    static Dune::MPIHelper::MPICommunicator comm;
-    return comm;
-#endif
-}
-}
-
 /*!
  * \ingroup Newton
  * \brief The multi-dimensional Newton method.
@@ -205,7 +192,7 @@ public:
         : simulator_(simulator)
         , endIterMsgStream_(std::ostringstream::out)
         , linearSolver_(simulator)
-        , comm_(detail::getMPIHelperCommunicator())
+        , comm_(Dune::MPIHelper::getCommunicator())
         , convergenceWriter_(asImp_())
     {
         lastError_ = 1e100;