upstream: fix interaction between ClientAliveInterval and RekeyLimit

that could cause connection to close incorrectly; Report and patch from Jakub
Jelen in bz#2757; ok dtucker@ markus@

OpenBSD-Commit-ID: 17229a8a65bd8e6c2080318ec2b7a61e1aede3fb

serverloop.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.214 2019/03/06 21:06:59 dtucker Exp $ */
+/* $OpenBSD: serverloop.c,v 1.215 2019/03/27 09:29:14 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -248,9 +248,10 @@ wait_until_can_do_something(struct ssh *ssh,
 		uint64_t keepalive_ms =
 		    (uint64_t)options.client_alive_interval * 1000;
 
-		client_alive_scheduled = 1;
-		if (max_time_ms == 0 || max_time_ms > keepalive_ms)
+		if (max_time_ms == 0 || max_time_ms > keepalive_ms) {
 			max_time_ms = keepalive_ms;
+			client_alive_scheduled = 1;
+		}
 	}
 
 #if 0