pf: Update packetfilter to OpenBSD 4.4

pf: Update packetfilter to OpenBSD 4.4

        * As correct pf function depends directly on pfsync now
          compile if_pfsyn.c into pf.ko. pflog is already part
          of pf.ko.

        * Activate pfsync function by default. It's not a kernel
          option anymore, but pfsync is very unlikley to work.
          Anyway our ifconfig is missing all pfsync related options.
          I will try to make pfsync working again after upgrading to
          pf from OpenBSD 4.5 as pfsync changes completley then
          and is not compatible anymore with prior versions.

        * Also make the module unloading sane in if_pflog.c

        Thanks to Alex Hornung and Aggelos Economopoulos for debugging.