Following the license change, modify the boilerplates in ssl/

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7768)

ssl/ssl_stat.c

diff --git a/ssl/ssl_stat.c b/ssl/ssl_stat.c
index 179513b..da8f5ed 100644
--- a/ssl/ssl_stat.c
+++ b/ssl/ssl_stat.c
@@ -2,7 +2,7 @@
  * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
  * Copyright 2005 Nokia. All rights reserved.
  *
- * Licensed under the OpenSSL license (the "License").  You may not use
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html