upstream: Add experimental support for PQC XMSS keys (Extended

Hash-Based Signatures) The code is not compiled in by default (see WITH_XMSS
in Makefile.inc) Joint work with stefan-lukas_gazdag at genua.eu See
https://tools.ietf.org/html/draft-irtf-cfrg-xmss-hash-based-signatures-12 ok
djm@

OpenBSD-Commit-ID: ef3eccb96762a5d6f135d7daeef608df7776a7ac
diff --git a/servconf.c b/servconf.c
index bf8ad67..c87a9a2 100644
--- a/servconf.c
+++ b/servconf.c
@@ -1,5 +1,5 @@
 
-/* $OpenBSD: servconf.c,v 1.324 2018/02/16 02:32:40 djm Exp $ */
+/* $OpenBSD: servconf.c,v 1.325 2018/02/23 15:58:37 markus Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -253,6 +253,8 @@
 #endif
 		servconf_add_hostkey("[default]", 0, options,
 		    _PATH_HOST_ED25519_KEY_FILE);
+		servconf_add_hostkey("[default]", 0, options,
+		    _PATH_HOST_XMSS_KEY_FILE);
 	}
 	/* No certificates by default */
 	if (options->num_ports == 0)