Add server side support for TLSv1.3 downgrade mechanism

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3022)
diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c
index d584bd7..0490813 100644
--- a/ssl/statem/statem_clnt.c
+++ b/ssl/statem/statem_clnt.c
@@ -1094,7 +1094,8 @@
     } else
         i = 1;
 
-    if (i && ssl_fill_hello_random(s, 0, p, sizeof(s->s3->client_random)) <= 0)
+    if (i && ssl_fill_hello_random(s, 0, p, sizeof(s->s3->client_random),
+                                   DOWNGRADE_NONE) <= 0)
         return 0;
 
     /*-