New preview patch for ipfw to pfil_hooks conversion

Here is the next preview patch for the ipfw to pfil_hooks conversion:

  http://www.nrg4u.com/freebsd/ipfw-pfilhooks-and-more-20040621.diff

This patch significantly cleans up ip_input.c and ip_output.c.

The following is included in this patch:

  o Remove all ipfw related cruft from ip_input() and ip_output()
  o New ip_fw_pfil.c file which contains all ipfw/pfil_hooks logic

  o ipfw firewalling, divert and dummynet works fine

  o ipfw forward is not yet implemented again (comes next)
  o ipfw layer2 is not yet implemented again (comes next)

  o ip_reass() is a self-contained function now (external code only relocated)

  o All IP Options related functions of ip_input/ip_output are moved into their
    own ip_options.[ch] file to have them together in one place

  o Some other small work in progress

Consider this a FYI.  It is very much a WIP at the moment.  I want to get this
into the tree in before 5.3 code freeze.

-- 
Andre