ANDROID: netfilter: xt_quota2: add quota2 from xtables-addons

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.

Therefore this patch adds xt_quota2, derived from
"extensions/xt_quota2.c" from xtables-addons
(https://sourceforge.net/projects/xtables-addons

)
at commit e84391ce665cef046967f796dd91026851d6bbf3.

[CPNOTE: 20/07/21] Lee: Poked the bug

Bug: 120445421
Change-Id: I19d49858840effee9ecf6cff03c23b45a97efdeb
Signed-off-by: JP Abgrall <jpa@google.com>
[adelva: Folded 4d33aa305871 ("netfilter: xt_quota2: fixup the quota2,
         and enable.") into this patch]
Signed-off-by: Alistair Delva <adelva@google.com>
[maennich: Folded eab89421 ("ANDROID: fix kernelci build-break")
           into this patch]
Signed-off-by: Matthias Maennich <maennich@google.com>
[ebiggers: Folded in the following commits:
           8a35207f ("ANDROID: fix up xt_quota2 for proc_ops changes")
           91e5e077 ("ANDROID: move up spin_unlock_bh() ahead of remove_proc_entry()").
           b20eacd8 ("ANDROID: fix a bug in quota2")
           Also updated the commit message.]
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Lee Jones <joneslee@google.com>