upstream: Add $OpenBSD$ markers to xmss files to help keep synced

with portable. ok djm@.

OpenBSD-Commit-ID: 5233a27aafd1dfadad4b957225f95ae51eb365c1
diff --git a/xmss_hash.c b/xmss_hash.c
index f90e056..b9eee7c 100644
--- a/xmss_hash.c
+++ b/xmss_hash.c
@@ -1,3 +1,4 @@
+/* $OpenBSD: xmss_hash.c,v 1.2 2018/02/26 03:56:44 dtucker Exp $ */
 /*
 hash.c version 20160722
 Andreas Hülsing