sys: Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

pfsync: prepare code to accommodate AF_INET6 family

Work is ongoing to add support for pfsync over IPv6. This required some
changes to allow for differentiating between the two families in a more
generic way.

This patch converts the relevant ioctls to using nvlists, making future
extensions (such as supporting IPv6 addresses) easier.

Sponsored by: InnoGames GmbH
Differential Revision: https://reviews.freebsd.org/D36277

pflog/pfsync: Fix module build with VIMAGE=yes

pflog and pfsync's module Makefile fails to include opt_global.h to SRCS
leading to build error for VIMAGE case.

Reproduced with:
cd /usr/src/sys/modules/pflog && make VIMAGE=yes

PR: 229404
Submitted by: eugen@
MFC after: 1 week

sys/modules: normalize .CURDIR-relative paths to SRCTOP

This simplifies make output/logic

Tested with: `cd sys/modules; make ALL_MODULES=` on amd64
MFC after: 1 month
Sponsored by: Dell EMC Isilon

Remove the old depend (mkdep) code and make FAST_DEPEND the one true way.

Reviewed by: emaste, hselasky (partial), brooks (brief)
Discussed on: arch@
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D5742

Move most of the 15 variations on generating opt_inet.h and
opt_inet6.h into kmod.mk by forcing almost everybody to eat the same
dogfood. While at it, consolidate the opt_bpf.h and opt_mroute.h
targets here too.

Use src.opts.mk in preference to bsd.own.mk except where we need stuff
from the latter.

o Create directory sys/netpfil, where all packet filters should
reside, and move there ipfw(4) and pf(4).

o Move most modified parts of pf out of contrib.

Actual movements:

sys/contrib/pf/net/*.c -> sys/netpfil/pf/
sys/contrib/pf/net/*.h -> sys/net/
contrib/pf/pfctl/*.c -> sbin/pfctl
contrib/pf/pfctl/*.h -> sbin/pfctl
contrib/pf/pfctl/pfctl.8 -> sbin/pfctl
contrib/pf/pfctl/*.4 -> share/man/man4
contrib/pf/pfctl/*.5 -> share/man/man5

sys/netinet/ipfw -> sys/netpfil/ipfw

The arguable movement is pf/net/*.h -> sys/net. There are
future plans to refactor pf includes, so I decided not to
break things twice.

Not modified bits of pf left in contrib: authpf, ftp-proxy,
tftp-proxy, pflogd.

The ipfw(4) movement is planned to be merged to stable/9,
to make head and stable match.

Discussed with: bz, luigi

In FreeBSD we always have bpf(4) API, either real or stub. No need
in detecting presense of 'device bpf'.

Prepare for pf 3.5 import:
- Remove pflog and pfsync modules. Things will change in such a fashion
that there will be one module with pf+pflog that can be loaded into
GENERIC without problems (which is what most people want). pfsync is no
longer possible as a module.
- Add multicast address for in-kernel multicast pfsync protocol. Protocol
glue will follow once the import is done.
- Add one more mbuf tag

Make pf* modules respect NOINET6 from make.conf(5) in order to build them
for INET6-less kernel.

Requested by: many
Approved by: bms(mentor)

Tweak existing header and other build infrastructure to be able to build
pf/pflog/pfsync as modules. Do not list them in NOTES or modules/Makefile
(i.e. do not connect it to any (automatic) builds - yet).

Approved by: bms(mentor)