contrib/check-config.sh: fix NF_NAT_NEEDED

CONFIG_NF_NAT_NEEDED was removed in kernel commit 4806e975729f99c7,
which made its way into v5.2-rc1. The functionality is now under
NF_NAT which we already check for.

Make the check for NF_NAT_NEEDED conditional.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

contrib/check-config.sh

@@ -198,7 +198,7 @@ flags=(
 	VETH BRIDGE BRIDGE_NETFILTER
 	IP_NF_FILTER IP_NF_TARGET_MASQUERADE
 	NETFILTER_XT_MATCH_{ADDRTYPE,CONNTRACK,IPVS}
-	IP_NF_NAT NF_NAT NF_NAT_NEEDED
+	IP_NF_NAT NF_NAT
 
 	# required for bind-mounting /dev/mqueue into containers
 	POSIX_MQUEUE
@@ -212,6 +212,10 @@ if [ "$kernelMajor" -lt 5 ] || [ "$kernelMajor" -eq 5 -a "$kernelMinor" -le 1 ];
 	check_flags NF_NAT_IPV4
 fi
 
+if [ "$kernelMajor" -lt 5 ] || [ "$kernelMajor" -eq 5 -a "$kernelMinor" -le 2 ]; then
+	check_flags NF_NAT_NEEDED
+fi
+
 echo
 
 echo 'Optional Features:'