Let phutil_rebuild_map show a progress bar

Summary: .. Instead of dots that are hard to count.

Test Plan: remove .phutil_module_cache and do arc liberate

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9584