Merge pull request #46674 from neersighted/backport/46667/20.10

[20.10 backport] Add IP_NF_MANGLE to check-config.sh

contrib/check-config.sh

@@ -196,7 +196,7 @@ flags=(
 	CGROUPS CGROUP_CPUACCT CGROUP_DEVICE CGROUP_FREEZER CGROUP_SCHED CPUSETS MEMCG
 	KEYS
 	VETH BRIDGE BRIDGE_NETFILTER
-	IP_NF_FILTER IP_NF_TARGET_MASQUERADE
+	IP_NF_FILTER IP_NF_MANGLE IP_NF_TARGET_MASQUERADE
 	NETFILTER_XT_MATCH_{ADDRTYPE,CONNTRACK,IPVS}
 	NETFILTER_XT_MARK
 	IP_NF_NAT NF_NAT