• Include support for AMD GPUs with HIP programming.
• Allow runtime SUPERLU_ACC_OFFLOAD = 0 to disable GPU offload for both
  2D and 3D codes.
• Include mixed-precision routines: 'psdrive' (single working precision)
  can take double-precision iterative refinement as an option.
• Add the fields in 'options' input structure, corresponding to the
  parameters that are changeable by environment variables.
• Add GPU stats variables in SuperLUStat_t{}, print the same way as CPU.