Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Switch the default WARNS level for sbin/ to 6.

Submitted by: Ulrich Spörlein

Link pf 4.1 to the build:
- move ftp-proxy from libexec to usr.sbin
- add tftp-proxy
- new altq mtag link

Approved by: re (kensmith)

Add missing library dependencies.

Adapt Makefiles for pfctl(8) and authpf(8) to 3.7 sources.

Remove -I from CFLAGS. This splipped in with the 3.5 import (as I was
building on a box with older pfvar.h installed). Didn't intend to commit it.

Requested by: ru (on a C&P to ipfw's Makefile)

Removed redundant and unsafe BINDIR redefinition.

Commit userland part of pf version 3.5 from OpenBSD (OPENBSD_3_5_BASE).

Add skeleton build dirs for pf userland:
libexec/ftp-proxy - ftp proxy for pf
sbin/pfctl - equivalent to sbin/ipf
sbin/pflogd - deamon logging packets via if_pflog in pcap format
usr.sbin/authpf - authentification shell to modify pf rulesets

Bring along some altq headers used to satisfy pfctl/authpf compile. This
helps to keep the diff down and will make it easy to have a altq-patchset
use the full powers of pf.

Also make sure that the pf headers are installed.

This does not link anything to the build. There will be a NO_PF switch for
make.conf once pf userland is linked.

Approved by: bms(mentor)