git: network.subr: Support IPv6 in dhcpif()

[Aaron LI]

commit 329743def50a061489debcd9682983235c8f5b42
Author: Aaron LI <***@aaronly.me>
Date: Wed Nov 14 17:49:03 2018 +0800

network.subr: Support IPv6 in dhcpif()

Extend the 'dhcpif()' to support checking the interface needs DHCP for
IPv4-only, IPv6-only or either.

The 'dhcpcd' rc script in the following commit will use this new feature
to determine whether dhcpcd should do DHCPv4 or DHCPv6 or both.

Summary of changes:
etc/network.subr | 41 +++++++++++++++++++++++++++++++----------
1 file changed, 31 insertions(+), 10 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/329743def50a061489debcd9682983235c8f5b42