Remove direct usage of VTK-m in LOD test

The direct use of VTK-m was to switch the device being used.

TODO: add a means of specifying the device a VTK-m filter in
vtkAcceleratorsVTKm should use without directly interfacing with VTK-m.

Accelerators/Vtkm/Testing/Cxx/TestVTKMLevelOfDetail.cxx

@@ -13,6 +13,11 @@
 
 =========================================================================*/
 
+// Uncomment this to directly compare serial and TBB versions
+// #define FORCE_VTKM_DEVICE
+
+// TODO: Make a way to force the VTK-m device without actually loading VTK-m
+// headers (and all subsequent dependent headers).
 
 #include "vtkActor.h"
 #include "vtkCamera.h"
@@ -46,11 +51,15 @@
 #include "vtkWindowToImageFilter.h"
 #include "vtkXMLPolyDataReader.h"
 
+#ifdef FORCE_VTKM_DEVICE
+
 #include <vtkm/cont/RuntimeDeviceTracker.h>
 
 #include <vtkm/cont/serial/DeviceAdapterSerial.h>
 #include <vtkm/cont/tbb/DeviceAdapterTBB.h>
 
+#endif // FORCE_VTKM_DEVICE
+
 #include <iomanip>
 #include <sstream>
 
@@ -298,6 +307,8 @@ void RunBenchmark(int gridSize)
 #endif
   }
 
+#ifdef FORCE_VTKM_DEVICE
+
   vtkm::cont::RuntimeDeviceTracker tracker =
       vtkm::cont::GetGlobalRuntimeDeviceTracker();
 
@@ -326,6 +337,19 @@ void RunBenchmark(int gridSize)
   }
 #endif // VTKM_ENABLE_TBB
 
+#else // !FORCE_VTKM_DEVICE
+
+  // Run VTKm
+  vtkSmartPointer<vtkPolyData> vtkmResult;
+  double vtkmTime = 0.;
+  {
+    VTKmFilterGenerator generator(gridSize);
+    vtkmTime = BenchmarkFilter(generator, input);
+    vtkmResult = generator.Result;
+  }
+
+#endif
+
   // Run VTK -- average clustered points
   vtkSmartPointer<vtkPolyData> vtkResultAvePts;
   double vtkTimeAvePts = 0.;
@@ -349,6 +373,8 @@ void RunBenchmark(int gridSize)
             << "Input dataset has " << input->GetNumberOfPoints() << " points "
                "and " << input->GetNumberOfCells() << " cells.\n";
 
+#ifdef FORCE_VTKM_DEVICE
+
   std::cerr << "vtkmLevelOfDetail (serial, average clustered points): "
             << vtkmTimeSerial << " seconds, "
             << vtkmResultSerial->GetNumberOfPoints() << " points, "
@@ -364,6 +390,15 @@ void RunBenchmark(int gridSize)
   }
 #endif // VTKM_ENABLE_TBB
 
+#else // !FORCE_VTKM_DEVICE
+
+  std::cerr << "vtkmLevelOfDetail (average clustered points): "
+            << vtkmTime << " seconds, "
+            << vtkmResult->GetNumberOfPoints() << " points, "
+            << vtkmResult->GetNumberOfCells() << " cells.\n";
+
+#endif // !FORCE_VTKM_DEVICE
+
   std::cerr << "vtkQuadricClustering (average clustered points): "
             << vtkTimeAvePts << " seconds, "
             << vtkResultAvePts->GetNumberOfPoints() << " points, "
@@ -373,11 +408,17 @@ void RunBenchmark(int gridSize)
             << vtkResult->GetNumberOfPoints() << " points, "
             << vtkResult->GetNumberOfCells() << " cells.\n";
 
+#ifdef FORCE_VTKM_DEVICE
 #ifdef VTKM_ENABLE_TBB
   RenderResults(gridSize, input,
                 vtkmTimeTBB, vtkmResultTBB,
                 vtkTime, vtkResult);
 #endif // VTKM_ENABLE_TBB
+#else // !FORCE_VTKM_DEVICE
+  RenderResults(gridSize, input,
+                vtkmTime, vtkmResult,
+                vtkTime, vtkResult);
+#endif // !FORCE_VTKM_DEVICE
 }
 
 void RunBenchmarks()