Merge branch 'fix/linear-version-checks' into 'master'

[linear] Remove left-over version checks

See merge request !2007

dumux/linear/istlsolverfactorybackend.hh

@@ -295,6 +295,4 @@ private:
 
 } // end namespace Dumux
 
-#else
-#warning "Generic dune-istl solver factory backend needs dune-istl >= 2.7!"
 #endif // header guard

dumux/linear/istlsolverregistry.hh

@@ -25,11 +25,7 @@
 #ifndef DUMUX_LINEAR_ISTL_SOLVER_REGISTRY_HH
 #define DUMUX_LINEAR_ISTL_SOLVER_REGISTRY_HH
 
-#include <dune/common/version.hh>
-#if DUNE_VERSION_NEWER_REV(DUNE_ISTL,2,7,1)
-
 #include <dune/istl/common/registry.hh>
-#include <dune/istl/solverregistry.hh>
 
 /*!
  * \brief Register a Dumux preconditioner
@@ -52,5 +48,4 @@ struct MultiTypeBlockMatrixDirectSolverTag {};
 } // end namespace
 } // end namespace Dumux
 
-#endif // DUNE version check
 #endif // DUMUX_LINEAR_ISTL_SOLVER_REGISTRY_HH