use kokkos allocate when oldSize is zero
In vtkm/cont/internal/DeviceAdapterMemoryManager.cxx BufferInfo can be created using the default constructor with size = 0. Internals->memory and internals->container are then set to nullptr.
This causes the kokkos reallocator to throw a runtime exception.
Fix is to check if OldSize == 0 and call Allocate instead of Reallocate.
Edited by Abdelilah Essiari