!19 Fix uninstall error when service not stopped

From: @zhangsong234
Reviewed-by: @jing-rui
Signed-off-by: @jing-rui

lxcfs.spec

@@ -4,7 +4,7 @@
 #Basic Information
 Name:      lxcfs
 Version:   4.0.5
-Release:   2
+Release:   3
 Summary:   FUSE filesystem for LXC
 License:   Apache-2.0
 URL:       http://linuxcontainers.org
@@ -57,10 +57,11 @@ install -d -m 0755 %{buildroot}%{_localstatedir}/lib/lxc/%{name}/
 %pre
 
 %preun
+%systemd_preun lxcfs
 
 %post
-ret=`systemctl is-active lxcfs`
-if [ "$ret" == "active" ]; then
+systemctl status lxcfs | grep 'Active:' | grep 'running'
+if [ $? -eq 0 ]; then
 	systemctl restart lxcfs
 fi