Install systemd services with autotools

Change-Id: I103bf3468d53578045593eac31b61f7e0248495e
diff --git a/debian/osmo-gtphub.install b/debian/osmo-gtphub.install
index ed0bd1b..568caaf 100644
--- a/debian/osmo-gtphub.install
+++ b/debian/osmo-gtphub.install
@@ -1,3 +1,4 @@
+lib/systemd/system/osmo-gtphub.service
 usr/bin/osmo-gtphub
 usr/share/doc/osmo-sgsn/examples/osmo-gtphub/osmo-gtphub-1iface.cfg usr/share/doc/osmo-gtphub/examples
 usr/share/doc/osmo-sgsn/examples/osmo-gtphub/osmo-gtphub.cfg usr/share/doc/osmo-gtphub/examples