Install systemd services with autotools

Change-Id: I103bf3468d53578045593eac31b61f7e0248495e
diff --git a/Makefile.am b/Makefile.am
index 38fdcba..1883ab5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -12,6 +12,7 @@
 	doc \
 	include \
 	src \
+	contrib \
 	tests \
 	$(NULL)
 
@@ -21,6 +22,9 @@
 BUILT_SOURCES = $(top_srcdir)/.version
 EXTRA_DIST = git-version-gen osmoappdesc.py .version
 
+DISTCHECK_CONFIGURE_FLAGS = \
+	--with-systemdsystemunitdir=$$dc_install_base/$(systemdsystemunitdir)
+
 @RELMAKE@
 
 $(top_srcdir)/.version: