The following changes are added because of

The following changes are added because of
network_ipv6->rc.d/netif integration:

- $ipv6_enable is now obsolete.  Instead, IPv6 is enabled by
  default if the kernel supports it, and $ipv6_network_interfaces
  is "none" by default.  If you want to use IPv6, define
  $ipv6_network_interfaces and $ifconfig_xxx_ipv6.

  An interface which is in $network_interfaces and not in
  $ipv6_network_interfaces will be marked as "inet6
  -auto_linklocal ifdisabled" (see ifconfig(8)).

- $ipv6_ifconfig_xxx is renamed to ifconfig_xxx_ipv6 for
  consistency with other address families.  The old variables
  still work but can be removed in the future.  Note that
  ipv6_ifconfig_xxx="..." should be replaced with
  ifconfig_xxx_ipv6="inet6 ...".

- Receiving ICMPv6 Router Advertisement is not automatically
  enabled even if there is no manual configuration of IPv6 in
  rc.conf.  If you want it, define
  ifconfig_xxx_ipv6="inet6 ... accept_rtadv".

- The rc.d/ip6addrctl now chooses address selection policy based
  on $ipv6_prefer, not $ipv6_enable.  The default is
  ipv6_prefer=NO.

- $router* and $ipv6_router* are replaced with $routed_* and
  $route6d_* for consistency.  The old variables still work but
  can be removed in the future.

MFC after:	3 days