message: Avoid cudaErrorCudartUnloading error while freeing cuda memory at exit.
diff: do \
  { \
  cudaError_t err = (x); \
  - if (err != cudaSuccess) \
  + if (err != cudaSuccess && err != cudaErrorCudartUnloading) \
  { \
  mfem_cuda_error(err, #x, _MFEM_FUNC_NAME, __FILE__, __LINE__); \
  } \
  