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