BUILD/MEDIUM: tcp: set-mark support for OpenBSD

set-mark support for this platform, for routing table purpose.
Follow-up from f7f53afcf9d367d19, this time for OpenBSD.
diff --git a/src/tcp_act.c b/src/tcp_act.c
index b684bff..3596d31 100644
--- a/src/tcp_act.c
+++ b/src/tcp_act.c
@@ -237,7 +237,7 @@
 }
 
 
-#if defined(SO_MARK) || defined(SO_USER_COOKIE)
+#if defined(SO_MARK) || defined(SO_USER_COOKIE) || defined(SO_RTABLE)
 static enum act_return tcp_action_set_mark(struct act_rule *rule, struct proxy *px,
 					   struct session *sess, struct stream *s, int flags)
 {
@@ -308,7 +308,7 @@
 static enum act_parse_ret tcp_parse_set_mark(const char **args, int *cur_arg, struct proxy *px,
 					     struct act_rule *rule, char **err)
 {
-#if defined(SO_MARK) || defined(SO_USER_COOKIE)
+#if defined(SO_MARK) || defined(SO_USER_COOKIE) || defined(SO_RTABLE)
 	char *endp;
 	unsigned int mark;
 
@@ -331,7 +331,7 @@
 	global.last_checks |= LSTCHK_NETADM;
 	return ACT_RET_PRS_OK;
 #else
-	memprintf(err, "not supported on this platform (SO_MARK|SO_USER_COOKIE undefined)");
+	memprintf(err, "not supported on this platform (SO_MARK|SO_USER_COOKIE|SO_RTABLE undefined)");
 	return ACT_RET_PRS_ERR;
 #endif
 }