安装smartdns后有个警告，现在是可以手动启动，运行systemctl enable smartdns设备自动启动失败，报错如下：
Synchronizing state of smartdns.service with SysV service script with /usr/lib/systemd/systemd-sysv-install.
Executing: /usr/lib/systemd/systemd-sysv-install enable smartdns
Failed to execute /usr/lib/systemd/systemd-sysv-install: 没有那个文件或目录