Don't writing entries to slave log about binlog_checksum not existing on...

Don't writing entries to slave log about binlog_checksum not existing on master if log_warnings is <=1.

This solves the issue of getting a lot of unnecessary errors logged on the slave when connecting to MySQL or an old MariaDB version.


sql/slave.cc:
  Don't write that binlog_checksum doesn't exists on the master if log_warnings <= 1

sql/slave.cc

@@ -1669,12 +1669,16 @@ when it try to get the value of TIME_ZONE global variable from master.";
         goto slave_killed_err;
 
       if (mysql_errno(mysql) == ER_UNKNOWN_SYSTEM_VARIABLE)
+      {
+        /* Ignore this expected error if not a high error level */
+        if (global_system_variables.log_warnings > 1)
         {
           // this is tolerable as OM -> NS is supported
           mi->report(WARNING_LEVEL, mysql_errno(mysql),
                      "Notifying master by %s failed with "
                      "error: %s", query, mysql_error(mysql));
         }
+      }
       else
       {
         if (is_network_error(mysql_errno(mysql)))