[NETFILTER]: Fix NAT init order

As noticed by Phil Oester, the GRE NAT protocol helper is initialized
before the NAT core, which makes registration fail.

Change the linking order to make NAT be initialized first.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/Makefile

@@ -12,6 +12,7 @@ ip_nat_pptp-objs	:= ip_nat_helper_pptp.o ip_nat_proto_gre.o
 
 # connection tracking
 obj-$(CONFIG_IP_NF_CONNTRACK) += ip_conntrack.o
+obj-$(CONFIG_IP_NF_NAT) += ip_nat.o
 
 # conntrack netlink interface
 obj-$(CONFIG_IP_NF_CONNTRACK_NETLINK) += ip_conntrack_netlink.o
@@ -41,7 +42,7 @@ obj-$(CONFIG_IP_NF_IPTABLES) += ip_tables.o
 # the three instances of ip_tables
 obj-$(CONFIG_IP_NF_FILTER) += iptable_filter.o
 obj-$(CONFIG_IP_NF_MANGLE) += iptable_mangle.o
-obj-$(CONFIG_IP_NF_NAT) += iptable_nat.o ip_nat.o
+obj-$(CONFIG_IP_NF_NAT) += iptable_nat.o
 obj-$(CONFIG_IP_NF_RAW) += iptable_raw.o
 
 # matches