Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFH (r256768): don't report an error for no-op add / remove

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Default to AF_LOCAL instead of AF_INET sockets for non-family-specific
operations. This allows the query operations to work in non-IPv4 jails,
and will be necessary in a future of possible non-INET networking.

Approved by: bz (mentor)

correct type definition of option routine callback

Import interface groups from OpenBSD. This allows to group interfaces in
order to - for example - apply firewall rules to a whole group of
interfaces. This is required for importing pf from OpenBSD 3.9

Obtained from: OpenBSD (with changes)
Discussed on: -net (back in April)