Remove a passing .future

Hildeth's commit 81ad381c6ef98e84e90d7d4ac49dbff57dd87ad4 marked compiler
generated destructors with FLAG_COMPILER_GENERATED, so object.~chpl_destroy no
longer shows up as a candidate function in the error message in this test.
Merge pull request #675 from daviditen/removePassingDestructorFuture

Remove a passing .future

Hildeth's commit 81ad381 marked compiler
generated destructors with FLAG_COMPILER_GENERATED, so object.~chpl_destroy no
longer shows up as a candidate function in the error message in this test.