- The v6 BSD socket method was updated to use a single UDP BSD socket

- The v6 BSD socket method was updated to use a single UDP BSD socket
  no matter how many interfaces are involved, differentiating the
  interfaces the packets were received on by the interface index supplied
  by the OS.
- The relay agent no longer listens to the All DHCP Servers Multicast
  address.
- A bug was fixed in data_string_sprintfa() where va_start was only called
  once for two invocations of vsprintf() variants.
  [ISC-Bugs #17610b]