radvd: upgrade 1.14 -> 2.11

Changes can be found at http://www.litech.org/radvd/CHANGES-2.txt



Signed-off-by: Li Xin <lixin.fnst@cn.fujitsu.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>