Alphabetize `.arclint` linters

Summary: I'm a bit OCD with this, but I find the `.arclint` file easier to read if the keys are in alphabetical order.

Test Plan: N/A

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9802