gluon-radvd: externalize arguments

The arguments are now provided by gluon-mesh-batman-adv-core, so
gluon-radvd can be used with other mesh protocols.

[Matthias Schiffer: removed PROVIDES dependency]

package/gluon-mesh-batman-adv-core/files/lib/gluon/radvd/arguments

+#!/usr/bin/lua
+local site = require "gluon.site_config"
+print("-i br-client -p " .. site.prefix6)

package/gluon-radvd/Makefile

@@ -12,7 +12,7 @@ define Package/gluon-radvd
   SECTION:=gluon
   CATEGORY:=Gluon
   TITLE:=Advertise an IPv6 prefix from the node
-  DEPENDS:=+gluon-core +gluon-ebtables +gluon-mesh-batman-adv +uradvd
+  DEPENDS:=+gluon-core +uradvd
 endef
 
 define Package/gluon-radvd/description

package/gluon-radvd/files/etc/init.d/gluon-radvd

@@ -7,7 +7,9 @@ SERVICE_DAEMONIZE=1
 
 
 start() {
-	service_start /usr/sbin/uradvd -i br-client -p $(lua -e 'print(require("gluon.site_config").prefix6)')
+  [ -x /lib/gluon/radvd/arguments ] && {
+	service_start /usr/sbin/uradvd $(/lib/gluon/radvd/arguments)
+  }
 }
 
 stop() {