message: Remove a64fx 64 warning
diff: #define MFEM_SIMD_BYTES 64
  #define MFEM_ALIGN_BYTES 64
  #elif defined(__aarch64__) && defined(__ARM_FEATURE_SVE)
  -#warning SVE 64/64
  #define MFEM_SIMD_BYTES 64
  #define MFEM_ALIGN_BYTES 64
  #elif defined(__AVX__) || defined(__VECTOR4DOUBLE__)
  