Configure make to prepare Composer dependencies

Summary:
composer install will require ast PHP extension for phan,
even if --no-dev is set. A Makefile is probably easier
to use than --no-dev --ignore-platform-reqs.

Test Plan: make clean all

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1575