Install systemd services with autotools

Change-Id: I7e4dae6b8c1685e8a673c58a843c41fa0af1b35c
diff --git a/contrib/Makefile.am b/contrib/Makefile.am
index db6d0f5..ab410c7 100644
--- a/contrib/Makefile.am
+++ b/contrib/Makefile.am
@@ -1 +1,3 @@
+SUBDIRS = systemd
+
 EXTRA_DIST = ipa.py
diff --git a/contrib/systemd/Makefile.am b/contrib/systemd/Makefile.am
new file mode 100644
index 0000000..c0d95ff
--- /dev/null
+++ b/contrib/systemd/Makefile.am
@@ -0,0 +1,5 @@
+if HAVE_SYSTEMD
+EXTRA_DIST = osmo-mgw.service
+systemdsystemunit_DATA = \
+  osmo-mgw.service
+endif