Let phutil_rebuild_map really be quiet

Summary: Depends on D9586. The progress bar is written to stderr which results in bad stuff happening when you try run lint (PhutilLibraryLinter calls it)

Test Plan: run arc lint, see no more errors

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9587