package/systemd: explicitly --enable-microhttpd

Signed-off-by: Gabe Evans <gabe@hashrabbit.co>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[Thomas: fix commit title.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/systemd/systemd.mk

@@ -126,6 +126,7 @@ endif
 
 ifeq ($(BR2_PACKAGE_SYSTEMD_JOURNAL_GATEWAY),y)
 SYSTEMD_DEPENDENCIES += libmicrohttpd
+SYSTEMD_CONF_OPTS += --enable-microhttpd
 else
 SYSTEMD_CONF_OPTS += --disable-microhttpd
 endif