upstream: Don't send IUTF8 to servers that don't like them.

Some SSH servers eg "ConfD" drop the connection if the client sends the
new IUTF8 (RFC8160) terminal mode even if it's not set.  Add a bug bit
for such servers and avoid sending IUTF8 to them.  ok djm@

OpenBSD-Commit-ID: 26425855402d870c3c0a90491e72e2a8a342ceda
diff --git a/ttymodes.c b/ttymodes.c
index 8451396..f9fdb92 100644
--- a/ttymodes.c
+++ b/ttymodes.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ttymodes.c,v 1.32 2017/04/30 23:26:54 djm Exp $ */
+/* $OpenBSD: ttymodes.c,v 1.33 2018/02/16 04:43:11 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -56,6 +56,7 @@
 #include "log.h"
 #include "compat.h"
 #include "buffer.h"
+#include "compat.h"
 
 #define TTY_OP_END		0
 /*
@@ -308,9 +309,15 @@
 	buffer_put_char(&buf, OP); \
 	buffer_put_int(&buf, special_char_encode(tio.c_cc[NAME]));
 
+#define SSH_TTYMODE_IUTF8 42  /* for SSH_BUG_UTF8TTYMODE */
+
 #define TTYMODE(NAME, FIELD, OP) \
-	buffer_put_char(&buf, OP); \
-	buffer_put_int(&buf, ((tio.FIELD & NAME) != 0));
+	if (OP == SSH_TTYMODE_IUTF8 && (datafellows & SSH_BUG_UTF8TTYMODE)) { \
+		debug3("%s: SSH_BUG_UTF8TTYMODE", __func__); \
+	} else { \
+		buffer_put_char(&buf, OP); \
+		buffer_put_int(&buf, ((tio.FIELD & NAME) != 0)); \
+	}
 
 #include "ttymodes.h"