Use My::Platform

Put all path conversions in one file
Convert the --tmpdir  passed to "mysqld --verbose --help"

mysql-test/lib/t/Platform.t

@@ -0,0 +1,18 @@
+# -*- cperl -*-
+use Test::More qw(no_plan);
+use strict;
+
+use_ok ("My::Platform");
+use My::Platform;
+
+use File::Temp qw / tempdir /;
+my $dir = tempdir( CLEANUP => 1 );
+
+print "Running on Windows\n" if (IS_WINDOWS);
+print "Using ActiveState perl\n" if (IS_WIN32PERL);
+print "Using cygwin perl\n" if (IS_CYGWIN);
+
+print "dir: '$dir'\n";
+print "native: '".native_path($dir)."'\n";
+print "mixed: '".mixed_path($dir)."'\n";
+print "posix: '".posix_path($dir)."'\n";