Install systemd services with autotools

Change-Id: Ic4875b74bcf2b6232d915070b77fc202a03ef997
diff --git a/Makefile.am b/Makefile.am
index a838715..6018753 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,3 +1,6 @@
-SUBDIRS = doc src
+SUBDIRS = contrib doc src
 
 ACLOCAL_AMFLAGS = -I m4
+
+AM_DISTCHECK_CONFIGURE_FLAGS = \
+	--with-systemdsystemunitdir=$$dc_install_base/$(systemdsystemunitdir)