[test] Make work with older CMake versions

Fixes #860 (closed). Should be backported to releases/3.2.

test/freeflow/navierstokes/sincos/CMakeLists.txt

@@ -35,7 +35,7 @@ dumux_add_test(NAME test_ff_navierstokes_sincos_uzawapreconditioner_factory
               SOURCES main.cc
               LABELS freeflow
               TIMEOUT 5000
-              CMAKE_GUARD "( HAVE_UMFPACK AND DUNE_ISTL_VERSION GREATER_EQUAL 2.7 )"
+              CMAKE_GUARD "( HAVE_UMFPACK AND ( ( DUNE_ISTL_VERSION VERSION_GREATER 2.7 ) OR ( DUNE_ISTL_VERSION VERSION_EQUAL 2.7 ) ) )"
               COMPILE_DEFINITIONS LINEARSOLVER=IstlSolverFactoryBackend<LinearSolverTraits<GridGeometry>>
               COMMAND ${CMAKE_SOURCE_DIR}/bin/testing/runtest.py
               CMD_ARGS       --script fuzzy