build(deb): deb pkg enable/disable emqx system

deploy/packages/deb/debian/postinst

@@ -35,6 +35,12 @@ chmod -R 0755 /usr/lib/emqx/bin
 ln -s /usr/lib/emqx/bin/emqx /usr/bin/emqx
 ln -s /usr/lib/emqx/bin/emqx_ctl /usr/bin/emqx_ctl
 
+if systemctl status --no-pager; then
+    systemctl enable emqx;
+else
+    echo "systemd is not in use, skip enable emqx"
+fi
+
 case "$1" in
     configure)
     ;;

deploy/packages/deb/debian/postrm

@@ -55,6 +55,11 @@ case "$1" in
         if [ -d /usr/lib/emqx ]; then
                 rm -r /usr/lib/emqx
         fi
+
+        if pidof systemd; then
+          systemctl disable emqx;
+          rm -f /etc/systemd/emqx.service
+        fi
     ;;
 
     remove)