libostree: add systemd optional dependency

This option is available since v2018.3:
https://github.com/ostreedev/ostree/commit/17db0f15a79835b76ede6785120d237066c57d32

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libostree/libostree.mk

@@ -68,4 +68,13 @@ else
 LIBOSTREE_CONF_OPTS += --without-selinux
 endif
 
+ifeq ($(BR2_INIT_SYSTEMD),y)
+LIBOSTREE_CONF_OPTS += \
+	--with-libsystemd \
+	--with-systemdsystemunitdir=/usr/lib/systemd/system
+LIBOSTREE_DEPENDENCIES += systemd
+else
+LIBOSTREE_CONF_OPTS += --without-libsystemd
+endif
+
 $(eval $(autotools-package))