Work around Debian mishandling of systemd socket-activated units

If there is a backward compatibility sysvinit script, then
even socket-activated services are started automatically after
install/upgrade.

debian/postinst

@@ -29,6 +29,15 @@ case "$1" in
     ;;
 esac
 
+if [ -x /etc/init.d/rspamd ]; then
+    update-rc.d rspamd defaults >/dev/null
+    if [ -d /run/systemd/systemd ]; then
+        systemctl --system daemon-reload >/dev/null || true
+    else
+        invoke-rc.d rspamd start || exit $?
+    fi
+fi
+
 #DEBHELPER#
 
 exit 0

debian/postrm

@@ -1,6 +1,14 @@
 #!/bin/sh
 set -e
 
+if [ "$1" = "purge" ]; then
+   update-rc.d rspamd remove >/dev/null
+fi
+
+if [ -d /run/systemd/system ]; then
+    systemctl --system daemon-reload >/dev/null || true
+fi
+
 #DEBHELPER#
 
 case "$1" in

debian/prerm

@@ -0,0 +1,8 @@
+#!/bin/sh
+set -e
+
+if [ -x /etc/init.d/rspamd ] && ! [ -d /run/systemd/system ]; then
+    invoke-rc.d rspamd stop || exit $?
+fi
+
+#DEBHELPER#

debian/rules

@@ -32,5 +32,11 @@ override_dh_fixperms:
 	dh_fixperms
 	chmod 750 $(CURDIR)/debian/rspamd/var/lib/rspamd
 
+override_dh_systemd_enable:
+	dh_systemd_enable rspamd.socket
+
 override_dh_systemd_start:
-	dh_systemd_start --restart-after-upgrade
+	dh_systemd_start --restart-after-upgrade --no-start
+
+override_dh_installinit:
+	dh_installinit -n