MFC r196423

MFC r196423
  Fix ipfw's initialization functions to get the correct order of evaluation
  to allow vnet and non vnet operation. Move some functions from ip_fw_pfil.c
  to ip_fw2.c and mode to mostly using the SYSINIT and VNET_SYSINIT handlers
  instead of the modevent handler. Correct some spelling errors in comments
  in the affected code. Note this bug fixes a crash in NON VIMAGE kernels when
  ipfw is unloaded.

  This patch is a minimal patch for 8.0
  I have a much larger patch that actually fixes the underlying problems
  that will be applied after 8.0

Reviewed by:	zec@, rwatson@, bz@(earlier version)
Approved by:	re (rwatson)

git-svn-id: svn://svn.freebsd.org/base/stable/8@196424 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f