Externalize variables owned logically by pf_ruleset.c

merge yamt-pf42 branch.
(import newer pf from OpenBSD 4.2)

ok'ed by peter@. requested by core@

Resolve conflicts (pf from OpenBSD 3.7, userland part).

merge after importing pf from openbsd 3.6. (userland part)

some files were imported to the different places from the previous version.
v3_5:
etc/pf.conf
etc/pf.os
etc/spamd.conf
share/man/man4/p

merge after importing pf from openbsd 3.6. (userland part)

some files were imported to the different places from the previous version.
v3_5:
etc/pf.conf
etc/pf.os
etc/spamd.conf
share/man/man4/pf.4
share/man/man4/pflog.4
share/man/man5/pf.conf.5
share/man/man5/pf.os.5
share/man/man5/spamd.conf.5
v3_6:
dist/pf/etc/pf.conf
dist/pf/etc/pf.os
dist/pf/etc/spamd.conf
dist/pf/share/man/man4/pf.4
dist/pf/share/man/man4/pflog.4
dist/pf/share/man/man5/pf.conf.5
dist/pf/share/man/man5/pf.os.5
dist/pf/share/man/man5/spamd.conf.5

show more ...

PF from openbsd 3.5
massage pfctl to compile/run on netbsd. put reachover makefile for pfctl
into src/sbin.
reviewed by matt, perry, christos

PF from openbsd 3.5