message: fix: cmakedefine MFEM_USE_HIP
diff: // Requires a CUDA compiler (nvcc).
  #cmakedefine MFEM_USE_CUDA
  +// Build the HIP-enabled version of the MFEM library.
  +// Requires a HIP compiler (hipcc).
  +#cmakedefine MFEM_USE_HIP
  +
  // Enable MFEM functionality based on the RAJA library
  #cmakedefine MFEM_USE_RAJA
  