selftests: explicitly require kernel features needed by udpgro tests

commit 3327a9c ("selftests: add functionals test for UDP GRO")
make use of ipv6 NAT, but such a feature is not currently implied by
selftests. Since the 'ip[6]tables' commands may actually create nft rules,
depending on the specific user-space version, let's pull both NF and
NFT nat modules plus the needed deps.

Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Fixes: 3327a9c ("selftests: add functionals test for UDP GRO")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/config

@@ -14,3 +14,17 @@ CONFIG_IPV6_VTI=y
 CONFIG_DUMMY=y
 CONFIG_BRIDGE=y
 CONFIG_VLAN_8021Q=y
+CONFIG_NETFILTER=y
+CONFIG_NETFILTER_ADVANCED=y
+CONFIG_NF_CONNTRACK=m
+CONFIG_NF_NAT_IPV6=m
+CONFIG_NF_NAT_IPV4=m
+CONFIG_IP6_NF_IPTABLES=m
+CONFIG_IP_NF_IPTABLES=m
+CONFIG_IP6_NF_NAT=m
+CONFIG_IP_NF_NAT=m
+CONFIG_NF_TABLES=m
+CONFIG_NF_TABLES_IPV6=y
+CONFIG_NF_TABLES_IPV4=y
+CONFIG_NFT_CHAIN_NAT_IPV6=m
+CONFIG_NFT_CHAIN_NAT_IPV4=m