rpm: add services enabling/disabling logic

Since some systemd services are moved to other packages, appropriate
%post/%preun should contain the code to enable/disable them.

Fixes QubesOS/qubes-issues#2894

rpm_spec/core-agent.spec

@@ -432,6 +432,15 @@ sed 's/^net.ipv4.ip_forward.*/#\0/'  -i /etc/sysctl.conf
 
 /usr/lib/qubes/qubes-fix-nm-conf.sh
 
+%post networking
+%systemd_post qubes-firewall.service
+%systemd_post qubes-iptables.service
+%systemd_post qubes-network.service
+%systemd_post qubes-updates-proxy.service
+
+%post qrexec
+%systemd_post qubes-qrexec-agent.service
+
 %preun
 if [ "$1" = 0 ] ; then
     # no more packages left
@@ -444,6 +453,15 @@ if [ "$1" = 0 ] ; then
     fi
 fi
 
+%preun networking
+%systemd_preun qubes-firewall.service
+%systemd_preun qubes-iptables.service
+%systemd_preun qubes-network.service
+%systemd_preun qubes-updates-proxy.service
+
+%preun qrexec
+%systemd_preun qubes-qrexec-agent.service
+
 %postun
 if [ $1 -eq 0 ] ; then
     /usr/bin/glib-compile-schemas %{_datadir}/glib-2.0/schemas &> /dev/null || :