message: Fix initialization data race from commit
diff: @@ -36,19 +36,17 @@ RegistrationMap* GetRegistrationMap() {
  // device_type as its key, and an optimizer creator as the value.
  typedef std::unordered_map<string, PluginGraphOptimizerRegistry::Creator>
  PluginRegistrationMap;
  -PluginRegistrationMap* registered_plugin_optimizers = nullptr;
  PluginRegistrationMap* GetPluginRegistrationMap() {
  - if (registered_plugin_optimizers == nullptr)
  - registered_plugin_optimizers = new PluginRegistrationMap;
  + static PluginRegistrationMap* registered_plugin_optimizers =
  + new PluginRegistrationMap;
  return registered_plugin_optimizers;
  }
  // This map is a global map for registered plugin configs. It contains the
  // device_type as its key, and ConfigList as the value.
  typedef std::unordered_map<string, ConfigList> PluginConfigMap;
  -PluginConfigMap* plugin_config_map = nullptr;
  PluginConfigMap* GetPluginConfigMap() {
  - if (plugin_config_map == nullptr) plugin_config_map = new PluginConfigMap;
  + static PluginConfigMap* plugin_config_map = new PluginConfigMap;
  return plugin_config_map;
  }
  