Fix #6366.  Free the newpath in backup_directory_tests
Fix #6366.  Free the newpath in backup_directory_tests

Jun-Yuan/Percona-TokuBackup,kbauskar/Percona-TokuBackup,kbauskar/Percona-TokuBackup,guiquanz/Percona-TokuBackup,percona/Percona-TokuBackup,tplavcic/Percona-TokuBackup,percona/Percona-TokuBackup,kbauskar/Percona-TokuBackup,dbpercona/Percona-TokuBackup,tplavcic/Percona-TokuBackup,kbauskar/Percona-TokuBackup,Jun-Yuan/Percona-TokuBackup,tplavcic/Percona-TokuBackup,guiquanz/Percona-TokuBackup,dbpercona/Percona-TokuBackup,percona/Percona-TokuBackup,guiquanz/Percona-TokuBackup,Jun-Yuan/Percona-TokuBackup,tplavcic/Percona-TokuBackup,dbpercona/Percona-TokuBackup,guiquanz/Percona-TokuBackup,Jun-Yuan/Percona-TokuBackup,dbpercona/Percona-TokuBackup,percona/Percona-TokuBackup