message: Avoid superfluous creation of std::string.
diff: @@ -57,14 +57,14 @@ void DelegatingLogSink::log(const spdlog::details::log_msg& msg) {
  absl::ReleasableMutexLock lock(&format_mutex_);
  if (!formatter_) {
  lock.Release();
  - sink_->log(fmt::to_string(msg.raw));
  + sink_->log(absl::string_view(msg.raw.data(), msg.raw.size()));
  return;
  }
  fmt::memory_buffer formatted;
  formatter_->format(msg, formatted);
  lock.Release();
  - sink_->log(fmt::to_string(formatted));
  + sink_->log(absl::string_view(formatted.data(), formatted.size()));
  }
  DelegatingLogSinkPtr DelegatingLogSink::init() {
  