Planning: fixed a stop issue for planning thread pool.
Planning: fixed a stop issue for planning thread pool.

wanglei828/apollo,xiaoxq/apollo,ApolloAuto/apollo,ApolloAuto/apollo,wanglei828/apollo,xiaoxq/apollo,ycool/apollo,ycool/apollo,wanglei828/apollo,xiaoxq/apollo,ApolloAuto/apollo,jinghaomiao/apollo,ycool/apollo,ApolloAuto/apollo,xiaoxq/apollo,jinghaomiao/apollo,wanglei828/apollo,jinghaomiao/apollo,xiaoxq/apollo,wanglei828/apollo,wanglei828/apollo,ApolloAuto/apollo,ycool/apollo,ApolloAuto/apollo,ycool/apollo,xiaoxq/apollo,jinghaomiao/apollo,jinghaomiao/apollo,ycool/apollo,jinghaomiao/apollo