netfilter: adding the original quota2 from xtables-addons

The original xt_quota in the kernel is plain broken:
  - counts quota at a per CPU level
    (was written back when ubiquitous SMP was just a dream)
  - provides no way to count across IPV4/IPV6.

This patch is the original unaltered code from:
  http://sourceforge.net/projects/xtables-addons



  at commit e84391ce665cef046967f796dd91026851d6bbf3

Change-Id: I19d49858840effee9ecf6cff03c23b45a97efdeb
Signed-off-by: JP Abgrall <jpa@google.com>