6relayd: Announce RDNSS and DNSSL via RA

git-svn-id: svn://svn.openwrt.org/openwrt@34983 3c298f89-4303-0410-b956-a3cf2f4a3e73
odhcp6c: Add support for SNTP and SIP options

git-svn-id: svn://svn.openwrt.org/openwrt@34984 3c298f89-4303-0410-b956-a3cf2f4a3e73
ipv6-support: Update iteration
* Add support for blocking forwarding while address assignments
* Fix relay restarting function

git-svn-id: svn://svn.openwrt.org/openwrt@34985 3c298f89-4303-0410-b956-a3cf2f4a3e73