Fix lint when working on windows

Summary:
Fixes T4395.

Add quotes to ExecFuture strings on Windows to prevent cmd.exe from mucking up the command string.

Test Plan: Run arc lint on projects using phpcs. See everything working like it should.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: epriestley, Korvin

Maniphest Tasks: T4592, T4395

Differential Revision: https://secure.phabricator.com/D9348