test_densead: no reason to initialize MPI here

thus we no longer depend on dune-common

CMakeLists_files.cmake

@@ -384,6 +384,7 @@ list (APPEND TEST_SOURCE_FILES
       tests/test_ConditionalStorage.cpp
       tests/test_cubic.cpp
       tests/test_EvaluationFormat.cpp
+      tests/test_densead.cpp
       tests/test_fluidmatrixinteractions.cpp
       tests/test_fluidsystems.cpp
       tests/test_messagelimiter.cpp
@@ -400,7 +401,6 @@ list (APPEND TEST_SOURCE_FILES
 # tests that need to be linked to dune-common
 list(APPEND DUNE_TEST_SOURCE_FILES
       tests/test_co2brine_ptflash.cpp
-      tests/test_densead.cpp
       tests/test_immiscibleflash.cpp
       tests/test_ncpflash.cpp
       tests/test_pengrobinson.cpp