netfilter: xtables: add CT target

Add a new target for the raw table, which can be used to specify conntrack
parameters for specific connections, f.i. the conntrack helper.

The target attaches a "template" connection tracking entry to the skb, which
is used by the conntrack core when initializing a new conntrack.

Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 634d14a..4469d45 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -341,6 +341,18 @@
 
 	  To compile it as a module, choose M here.  If unsure, say N.
 
+config NETFILTER_XT_TARGET_CT
+	tristate '"CT" target support'
+	depends on NF_CONNTRACK
+	depends on IP_NF_RAW || IP6_NF_RAW
+	depends on NETFILTER_ADVANCED
+	help
+	  This options adds a `CT' target, which allows to specify initial
+	  connection tracking parameters like events to be delivered and
+	  the helper to be used.
+
+	  To compile it as a module, choose M here.  If unsure, say N.
+
 config NETFILTER_XT_TARGET_DSCP
 	tristate '"DSCP" and "TOS" target support'
 	depends on IP_NF_MANGLE || IP6_NF_MANGLE