message: Do not call get_full_state_root() when it is not needed
diff: @@ -607,9 +607,9 @@ namespace ccf
  size_t all_data_size) override
  {
  append(replicated, replicated_size, all_data, all_data_size);
  +#ifdef PBFT
  auto root = get_full_state_root();
  LOG_DEBUG_FMT("HISTORY: add_result {0} {1} {2}", id, version, root);
  -#ifdef PBFT
  results[id] = {version, root};
  if (on_result.has_value())
  on_result.value()({id, version, root});
  @@ -618,9 +618,9 @@ namespace ccf
  void add_result(kv::TxHistory::RequestID id, kv::Version version) override
  {
  +#ifdef PBFT
  auto root = get_full_state_root();
  LOG_DEBUG_FMT("HISTORY: add_result {0} {1} {2}", id, version, root);
  -#ifdef PBFT
  results[id] = {version, root};
  if (on_result.has_value())
  on_result.value()({id, version, root});
  