message: mtp: more factorize blake2b computation
diff: @@ -349,22 +349,10 @@ bool mtp_verify(const char* input, const uint32_t target,
  }
  //hash[prev_index]
  - block blockhash_prev;
  - copy_block(&blockhash_prev, &prev_block);
  - uint8_t blockhash_prev_bytes[ARGON2_BLOCK_SIZE];
  - StoreBlock(&blockhash_prev_bytes, &blockhash_prev);
  -
  - blake2b_state state_prev;
  - blake2b_init(&state_prev, MERKLE_TREE_ELEMENT_SIZE_B);
  - blake2b_4r_update(&state_prev, blockhash_prev_bytes, ARGON2_BLOCK_SIZE);
  -
  uint8_t digest_prev[MERKLE_TREE_ELEMENT_SIZE_B];
  - blake2b_4r_final(&state_prev, digest_prev, sizeof(digest_prev));
  -
  + compute_blake2b(prev_block, digest_prev);
  MerkleTree::Buffer hash_prev(digest_prev,
  digest_prev + sizeof(digest_prev));
  - clear_internal_memory(blockhash_prev.v, ARGON2_BLOCK_SIZE);
  - clear_internal_memory(blockhash_prev_bytes, ARGON2_BLOCK_SIZE);
  if (!MerkleTree::checkProofOrdered(proof_blocks[(j * 3) - 2],
  root, hash_prev, ij_prev + 1)) {
  LogPrintf("error : checkProofOrdered in x[ij_prev]\n");
  