Merge from head/ 220800,220837,220914:

Merge from head/ 220800,220837,220914:

Log:
  LibAliasInit() should allocate memory with M_WAITOK flag. Modify it
  and its callers.

Log:
  - Rewrite functions that copyin/out NAT configuration, so that they
    calculate required memory size dynamically.
  - Fix races on chain re-lock.
  - Introduce new field to ip_fw_chain - generation count. Now utilized
    only in the NAT configuration, but can be utilized wider in ipfw.
  - Get rid of NAT_BUF_LEN in ip_fw.h

  PR:           kern/143653

git-svn-id: svn://svn.freebsd.org/base/stable/8@223872 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f