build: add correct libsystemd dependency

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ia6bb8d347f76ec3a6e8f8babe7da3e63cab907c0
diff --git a/phosphor-rsyslog-config/Makefile.am b/phosphor-rsyslog-config/Makefile.am
index 3a1aeff..e2890cc 100644
--- a/phosphor-rsyslog-config/Makefile.am
+++ b/phosphor-rsyslog-config/Makefile.am
@@ -15,9 +15,11 @@
 
 phosphor_rsyslog_conf_LDFLAGS = \
 	$(SDBUSPLUS_LIBS) \
+	$(SYSTEMD_LIBS) \
 	$(PHOSPHOR_DBUS_INTERFACES_LIBS)
 
 phosphor_rsyslog_conf_CXXFLAGS = \
 	$(SDBUSPLUS_CFLAGS) \
+	$(SYSTEMD_CFLAGS) \
 	$(PHOSPHOR_DBUS_INTERFACES_CFLAGS) \
 	-flto