The file tree in mtr's vardir has changed so an old
hard-coded path in mysql-test/t/subselect.test didn't
work.
Fix: update the paths in the test.


mysql-test/r/subselect.result:
  Updated result file.
mysql-test/t/subselect.test:
  Problem: The file tree in mtr's vardir has changed
  so an old hard-coded path didn't work.
  Fix: update the paths in the test.