message: logger: increment a counter when we dispatch a log event
diff: // Copyright (c) The Libra Core Contributors
  // SPDX-License-Identifier: Apache-2.0
  -use crate::{Event, Metadata};
  +use crate::{counters::STRUCT_LOG_COUNT, Event, Metadata};
  use once_cell::sync::OnceCell;
  use std::sync::Arc;
  @@ -19,6 +19,7 @@ pub trait Logger: Sync + Send + 'static {
  pub(crate) fn dispatch(event: &Event) {
  if let Some(logger) = LOGGER.get() {
  + STRUCT_LOG_COUNT.inc();
  logger.record(event)
  }
  }
  