use dune-alugrid instead of the old version from dune-grid if the module is available

examples/fracture_discretefracture.cpp

@@ -23,11 +23,6 @@
  */
 #include "config.h"
 
-#if !HAVE_ALUGRID
-#warning "The ALUGrid Dune grid manager is required for this test."
-int main(int argc, char **argv)
-{}
-#else
 #include <ewoms/common/start.hh>
 #include "problems/fractureproblem.hh"
 
@@ -36,5 +31,3 @@ int main(int argc, char **argv)
     typedef TTAG(FractureProblem) ProblemTypeTag;
     return Ewoms::start<ProblemTypeTag>(argc, argv);
 }
-
-#endif