[NETFILTER] ip_tables: NUMA-aware allocation

Part of a performance problem with ip_tables is that memory allocation
is not NUMA aware, but 'only' SMP aware (ie each CPU normally touch
separate cache lines)

Even with small iptables rules, the cost of this misplacement can be
high on common workloads.  Instead of using one vmalloc() area
(located in the node of the iptables process), we now allocate an area
for each possible CPU, using vmalloc_node() so that memory should be
allocated in the CPU's node if possible.

Port to arp_tables and ip6_tables by Harald Welte.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>