netfilter: add protocol independent NAT core

Convert the IPv4 NAT implementation to a protocol independent core and
address family specific modules.

Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 1c5160f..09c9451 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -43,6 +43,17 @@
 obj-$(CONFIG_NF_CONNTRACK_SIP) += nf_conntrack_sip.o
 obj-$(CONFIG_NF_CONNTRACK_TFTP) += nf_conntrack_tftp.o
 
+nf_nat-y	:= nf_nat_core.o nf_nat_proto_unknown.o nf_nat_proto_common.o \
+		   nf_nat_proto_udp.o nf_nat_proto_tcp.o nf_nat_helper.o
+
+obj-$(CONFIG_NF_NAT) += nf_nat.o
+obj-$(CONFIG_NF_NAT) += xt_nat.o
+
+# NAT protocols (nf_nat)
+obj-$(CONFIG_NF_NAT_PROTO_DCCP) += nf_nat_proto_dccp.o
+obj-$(CONFIG_NF_NAT_PROTO_UDPLITE) += nf_nat_proto_udplite.o
+obj-$(CONFIG_NF_NAT_PROTO_SCTP) += nf_nat_proto_sctp.o
+
 # transparent proxy support
 obj-$(CONFIG_NETFILTER_TPROXY) += nf_tproxy_core.o