netfilter: xtables: move ipt_ecn to xt_ecn

Prepare the ECN match for augmentation by an IPv6 counterpart. Since
no symbol dependencies to ipv6.ko are added, having a single ecn match
module is the more so welcome.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index b2eee4d..40f4c3d 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -81,6 +81,7 @@
 obj-$(CONFIG_NETFILTER_XT_MATCH_DCCP) += xt_dccp.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_DEVGROUP) += xt_devgroup.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_DSCP) += xt_dscp.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_ECN) += xt_ecn.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_ESP) += xt_esp.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_HASHLIMIT) += xt_hashlimit.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_HELPER) += xt_helper.o