Test test_meshing_polyhedron with TBB

One wants to compile and test the TBB and the non-TBB version of Mesh_3
in a single test.

Mesh_3/test/Mesh_3/test_meshing_polyhedron.cpp

@@ -26,7 +26,7 @@
 #include <CGAL/Polyhedral_mesh_domain_3.h>
 #include <CGAL/IO/Polyhedron_iostream.h>
 
-template <typename K>
+template <typename K, typename Concurrency_tag = CGAL::Sequential_tag>
 struct Polyhedron_tester : public Tester<K>
 {
   void polyhedron() const
@@ -35,14 +35,10 @@ struct Polyhedron_tester : public Tester<K>
     typedef CGAL::Polyhedron_3<Gt> Polyhedron;
     typedef CGAL::Polyhedral_mesh_domain_3<Polyhedron, Gt> Mesh_domain;
     
-#ifdef CGAL_CONCURRENT_MESH_3
-    typedef CGAL::Mesh_triangulation_3<
+    typedef typename CGAL::Mesh_triangulation_3<
       Mesh_domain,
-      CGAL::Kernel_traits<Mesh_domain>::Kernel,
-      CGAL::Parallel_tag>::type Tr;
-#else
-    typedef CGAL::Mesh_triangulation_3<Mesh_domain>::type Tr;
-#endif
+      typename CGAL::Kernel_traits<Mesh_domain>::Kernel,
+      Concurrency_tag>::type Tr;
     typedef CGAL::Mesh_complex_3_in_triangulation_3<Tr> C3t3;
     
     typedef CGAL::Mesh_criteria_3<Tr> Mesh_criteria;
@@ -92,6 +88,15 @@ int main()
   Polyhedron_tester<K_e_i> test_epic;
   std::cerr << "Mesh generation from a polyhedron:\n";
   test_epic.polyhedron();
-  
+
+#ifdef CGAL_LINKED_WITH_TBB
+  Polyhedron_tester<K_e_i, CGAL::Parallel_tag> test_epic_parallel;
+  std::cerr << "Mesh generation from a polyhedron using Parallel_tag:\n";
+  test_epic_parallel.polyhedron();
+#else
+  std::cerr << "TBB is not installed, or not configured."
+            << "The parallel version cannot be tested.\n";
+#endif
+
   return EXIT_SUCCESS;
 }