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

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

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

Update packet filter (pf) code to OpenBSD 4.5.

You need to update userland (world and ports) tools
to be in sync with the kernel.

Submitted by: mlaier
Submitted by: eri

Per email to arch@ a little while ago (that was greeted with silence),
prefer the more common > ${.TARGET} over > opt_foo.h in modules
makefiles.

Reimplementation of world/kernel build options. For details, see:

http://lists.freebsd.org/pipermail/freebsd-current/2006-March/061725.html

The src.conf(5) manpage is to follow in a few days.

Brought to you by: imp, jhb, kris, phk, ru (all bugs are mine)

The `pf' and `pflog' sources do not depend on DEV_PF or DEV_PFLOG,
which is normal for own files of a device driver.

DEV_FOO should be used if an unrelated kernel file needs to know of
the `foo' driver's static presence. Obviously, module source files
should never use DEV_*.

Make pflog a seperate module. As a result pflog_packet() becomes a function
pointer that is declared in pf_ioctl.c

Requested by: yar (as part of the module build reorg)
MFC after: 1 week
X-MFC with: yar's module reorg