message: Fix - seg fault on nodeos exit due to lib signal
diff: @@ -166,8 +166,7 @@ class producer_plugin_impl {
  }
  void on_irreversible_block( const signed_block_ptr& lib ) {
  - chain::controller& chain = app().get_plugin<chain_plugin>().chain();
  - _irreversible_block_age_us = chain.head_block_time() - lib->timestamp.to_time_point();
  + _irreversible_block_age_us = fc::time_point::now() - lib->timestamp.to_time_point();
  }
  template<typename Type, typename Channel, typename F>
  