[NETFILTER]: Add string match

Signed-off-by: Pablo Neira Ayuso <pablo@eurodev.net>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc include/linux/netfilter_ipv4/ipt_string.h
Simple merge

diff --cc net/ipv4/netfilter/Kconfig
Simple merge

diff --cc net/ipv4/netfilter/Makefile
Simple merge

diff --cc net/ipv4/netfilter/ipt_string.c
Simple merge