Use more sensible waitForAny semantics in SSH process

Summary: Ref T4189. Updates the Phabricator stuff to use the new, more sensible semantics from D7769. Basically, this works correctly now and doesn't need workarounds.

Test Plan: Pushed Wine repo in 1m13s.

Reviewers: btrahan, zeeg

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4189

Differential Revision: https://secure.phabricator.com/D7770