fix(mtr): backport bug for run mtr failed under low version perl (#73) (#74)

[summary]
Change is needed in MySQL 5.6 and 5.7 as well.
Signed-off-by: Nhustjieke <gaoriyao1@gmail.com>

client/mysqltest.cc

-/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2000, 2022, 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 as published by
@@ -35,6 +35,7 @@
 #include <my_dir.h>
 #include <hash.h>
 #include <stdarg.h>
+#include <string>
 #include <violite.h>
 #include "my_regex.h" /* Our own version of regex */
 #ifdef HAVE_SYS_WAIT_H
@@ -52,6 +53,7 @@
 
 using std::min;
 using std::max;
+using std::string;
 
 #ifdef __WIN__
 #include <crtdbg.h>
@@ -4237,7 +4239,11 @@ void do_perl(struct st_command *command)
       die("Failed to create temporary file for perl command");
     my_close(fd, MYF(0));
 
-    str_to_file(temp_file_path, ds_script.str, ds_script.length);
+    /* Compatibility for Perl 5.24 and newer. */
+    string script = "push @INC, \".\";\n";
+    script.append(ds_script.str, ds_script.length);
+
+    str_to_file(temp_file_path, &script[0], script.size());
 
     /* Format the "perl <filename>" command */
     my_snprintf(buf, sizeof(buf), "perl %s", temp_file_path);

mysql-test/mysql-test-run.pl

 #!/usr/bin/perl
 # -*- cperl -*-
 
-# Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2004, 2022, 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 as published by
@@ -100,6 +100,8 @@ use mtr_results;
 use IO::Socket::INET;
 use IO::Select;
 
+push @INC, ".";
+
 require "lib/mtr_process.pl";
 require "lib/mtr_io.pl";
 require "lib/mtr_gcov.pl";