Move a test file
Summary: This is a test case for ArcanistXHPASTLinter, not ArcanistPhutilXHPASTLinter.
Test Plan: arc unit
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin
Differential Revision: https://secure.phabricator.com/D13866