Bug#31893901 ADD GLOBAL MTR SUPPRESSION FOR IP ADDRESS ... COULD NOT BE RESOLVED

The server run by MTR on PB2 sometimes gets contacted by foreign
clients. Ignore warnings about not being able to resolve the IP
address.

Change-Id: Ia288385f6a76943534926c4e5a3f56c6fa4655e0

Author: dahlerlend

mysql-test/include/mtr_warnings.sql

@@ -1,4 +1,4 @@
--- Copyright (c) 2008, 2019, Oracle and/or its affiliates. All rights reserved.
+-- Copyright (c) 2008, 2020, Oracle and/or its affiliates. All rights reserved.
 --
 -- This program is free software; you can redistribute it and/or modify
 -- it under the terms of the GNU General Public License, version 2.0,
@@ -218,6 +218,10 @@ INSERT INTO global_suppressions VALUES
  ("==[0-9]*== Warning: invalid file descriptor -1 in syscall write()"),
  ("==[0-9]*== Warning: invalid file descriptor -1 in syscall read()"),
 
+ /* Suppress warnings caused by foreign clients, see Bug#31893901 */
+
+ ("IP address .* could not be resolved.*"),
+
  /*
    Transient network failures that cause warnings on reconnect.
    BUG#47743 and BUG#47983.