libnetfilter_conntrack: Add getter/setter for ids.

Index: libnetfilter_conntrack/src/conntrack/getter.c
===================================================================
@@ -157,6 +157,11 @@
 	return &ct->counters[__DIR_REPL].bytes;
 }
 
+static const void *get_attr_id(const struct nf_conntrack *ct)
+{
+	return &ct->id;
+}
+
 static const void *get_attr_status(const struct nf_conntrack *ct)
 {
 	return &ct->status;

@@ -199,5 +204,6 @@
 	[ATTR_REPL_COUNTER_PACKETS]	= get_attr_repl_counter_packets,
 	[ATTR_REPL_COUNTER_BYTES]	= get_attr_repl_counter_bytes,
 	[ATTR_USE]			= get_attr_use,
+	[ATTR_ID]			= get_attr_id,
 	[ATTR_STATUS]			= get_attr_status,
 };

Index: libnetfilter_conntrack/src/conntrack/setter.c
===================================================================
@@ -137,6 +137,11 @@
 	ct->mark = *((u_int32_t *) value);
 }
 
+static void set_attr_id(struct nf_conntrack *ct, const void *value)
+{
+	ct->id = *((u_int32_t *) value);
+}
+
 static void set_attr_status(struct nf_conntrack *ct, const void *value)
 {
 	ct->status = *((u_int32_t *) value);

@@ -169,5 +174,6 @@
 	[ATTR_DNAT_PORT]	= set_attr_dnat_port,
 	[ATTR_TIMEOUT]		= set_attr_timeout,
 	[ATTR_MARK]		= set_attr_mark,
+	[ATTR_ID]		= set_attr_id,
 	[ATTR_STATUS]		= set_attr_status,
 };