message: move cuda header to guards
diff: #include "../general/device.hpp"
  #include "../general/table.hpp"
  #include "../general/globals.hpp"
  -#include "../general/cuda.hpp"
  #include "densemat.hpp"
  #ifdef MFEM_USE_CUDA
  #include <cusparse.h>
  #include <library_types.h>
  +#include "../general/cuda.hpp"
  #endif
  namespace mfem
  