netfilter: xt_CT: add alias flag

This patch adds the alias flag to support full NOTRACK target
aliasing.

Based on initial patch from Jozsef Kadlecsik.

Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hi>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/xt_CT.h

@@ -3,7 +3,11 @@
 
 #include <linux/types.h>
 
-#define XT_CT_NOTRACK	0x1
+enum {
+	XT_CT_NOTRACK		= 1 << 0,
+	XT_CT_NOTRACK_ALIAS	= 1 << 1,
+	XT_CT_MASK		= XT_CT_NOTRACK | XT_CT_NOTRACK_ALIAS,
+};
 
 struct xt_ct_target_info {
 	__u16 flags;