nft: load only the tables of the current family

This changes nft_xtables_config_load() permit to load only
the tables of the current family.

[ This patch includes a fix for the configuration parser
  that I detected while testing this patch --pablo ]

Signed-off-by: Giuseppe Longo <giuseppelng@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2 files changed