contrib: fix makedistcheck with disabled systemd

EXTRA_DIST files need to be distributed, no matter if the systemd option
is configured or not.

Change-Id: Ic164403189510f3b20ff7906df09c78550735591
diff --git a/contrib/systemd/Makefile.am b/contrib/systemd/Makefile.am
index 520e720..eb33b4a 100644
--- a/contrib/systemd/Makefile.am
+++ b/contrib/systemd/Makefile.am
@@ -1,5 +1,6 @@
-if HAVE_SYSTEMD
 EXTRA_DIST = osmo-hlr.service
+
+if HAVE_SYSTEMD
 systemdsystemunit_DATA = \
   osmo-hlr.service
 endif