R1:d415641b029f

Allow XHProf to be publicly viewable

Summary: I guess... because PHP? Ref T4830

Test Plan: Log out, see pages.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T4830

Differential Revision: https://secure.phabricator.com/D13673