package/odhcp6c: add optional libubox dependency

libubox dependency has been added in
https://github.com/openwrt/odhcp6c/commit/33a2ba1c14eb5447326945c120e0b64a587ed151

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

package/odhcp6c/odhcp6c.mk

@@ -16,4 +16,11 @@ endef
 
 ODHCP6C_POST_INSTALL_TARGET_HOOKS += ODHCP6C_INSTALL_SCRIPT
 
+ifeq ($(BR2_PACKAGE_LIBUBOX),y)
+ODHCP6C_CONF_OPTS += -DUSE_LIBUBOX=1
+ODHCP6C_DEPENDENCIES += libubox
+else
+ODHCP6C_CONF_OPTS += -DUSE_LIBUBOX=0
+endif
+
 $(eval $(cmake-package))