Remove deprecated autoload module from libphutil

Summary:
This has been marked deprecated for like a week so I'm guessing either someone
fixed the use in trunk, it no longer exists, or it'll get fixed once it starts
fataling. :)

Test Plan:
Grepped for uses, none for many weeks.

Reviewed By: jungejason
Reviewers: tuomaspelkonen, jungejason
Commenters: aran
CC: aran, jungejason, epriestley
Differential Revision: 330