Merge branch 'fix/solver-factory-dune27' into 'master'

[linear][istlsolverfactorybackend] Fix compiler error for dune-2.7 and BCRS matrices

Closes #868

See merge request !2017

(cherry picked from commit c211d012)

dccae09f [linear][istlsolverfactorybackend] Fix compiler error for dune-2.7 and BCRS matrices

dumux/linear/istlsolverfactorybackend.hh

@@ -97,7 +97,15 @@ void initSolverFactories()
     if constexpr (isMultiTypeBlockMatrix<Matrix>::value)
         initSolverFactoriesForMultiTypeBlockMatrix<LinearOperator>();
     else
+#if DUNE_VERSION_GT(DUNE_ISTL,2,7)
         Dune::initSolverFactories<LinearOperator>();
+#else
+    {
+        using X  = typename LinearOperator::range_type;
+        using Y  = typename LinearOperator::domain_type;
+        Dune::initSolverFactories<Matrix, X, Y>();
+    }
+#endif
 }
 
 /*!