diy: correct mangling of vtkm_diy target
Use internal vtkm_ notation of diy target whether VTKm was the bottom most nested or the root project in a cmake invocation. This is needed for VTK.
backport: release
Edited by Vicente Bolea
Use internal vtkm_ notation of diy target whether VTKm was the bottom most nested or the root project in a cmake invocation. This is needed for VTK.
backport: release