innobackupex doesn't send tmpdir option to xtrabackup

When running a backup with innobackupex and --tmpdir specified it doesn't send --tmpdir to the child xtrabackup process so xbtemp* files get created with whatever is in your configuration file. If specified it should use the --tmpdir you tell it to.

Adding this code in the innobackupex function start_ibbackup() fixes it:

if ($option_tmpdir) {
        $options = $options. " --tmpdir=$option_tmpdir";
}