Install systemd services with autotools

Change-Id: Id81ae8e2d8a2c9456ac0dac2c30c0d24dab3b694
diff --git a/contrib/systemd/Makefile.am b/contrib/systemd/Makefile.am
new file mode 100644
index 0000000..520e720
--- /dev/null
+++ b/contrib/systemd/Makefile.am
@@ -0,0 +1,5 @@
+if HAVE_SYSTEMD
+EXTRA_DIST = osmo-hlr.service
+systemdsystemunit_DATA = \
+  osmo-hlr.service
+endif