Modernize ArcanistCpplintLinter.

Summary: Convert the cpplint.py wrapper linter to ArcanistExternalLinter. This is in preparation for T2039.

Test Plan: arc unit.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: epriestley, Korvin

Maniphest Tasks: T2039

Differential Revision: https://secure.phabricator.com/D9033