making AcceleratorVTKm optional

Here are the changes needed to make VTKm optional for the Moments filter.

MomentInvariants/vtkMomentInvariants.cxx

@@ -1574,7 +1574,6 @@ int vtkMomentInvariants::RequestData(vtkInformation* vtkNotUsed(request),
   vtkInformationVector** inputVector,
   vtkInformationVector* outputVector)
 {
-  vtkWarningMacro(<<"vtkMomentInvariants::RequestData")
   // get the info objects
   vtkInformation* patternInfo = inputVector[PatternPort]->GetInformationObject(0);
   vtkInformation* momentsInfo = inputVector[MomentPort]->GetInformationObject(0);