units: make networkd pull in its own .busname unit

The daemon requires the busname unit to operate (on kdbus systems),
since it contains the policy that allows it to acquire its service
name.

This fixes https://bugs.freedesktop.org/show_bug.cgi?id=90287

Makefile.am

@@ -5920,7 +5920,7 @@ gperf_gperf_sources += \
 	src/network/networkd-netdev-gperf.gperf
 
 EXTRA_DIST += \
-	units/systemd-networkd.service.in \
+	units/systemd-networkd.service.m4.in \
 	units/systemd-networkd-wait-online.service.in
 
 endif

units/.gitignore

@@ -48,6 +48,7 @@
 /systemd-modules-load.service
 /systemd-networkd-wait-online.service
 /systemd-networkd.service
+/systemd-networkd.service.m4
 /systemd-nspawn@.service
 /systemd-poweroff.service
 /systemd-quotacheck.service

units/systemd-networkd.service.m4.in

@@ -17,6 +17,13 @@ Before=network.target multi-user.target shutdown.target
 Conflicts=shutdown.target
 Wants=network.target
 
+m4_ifdef(`ENABLE_KDBUS',
+# On kdbus systems we pull in the busname explicitly, because it
+# carries policy that allows the daemon to acquire its name.
+Wants=org.freedesktop.network1.busname
+After=org.freedesktop.network1.busname
+
+)m4_dnl
 [Service]
 Type=notify
 Restart=on-failure