track necessary repos for inline toolchain building

Summary: this commit itself doesn't have dependencies, or break anything. It's needed by a few other submissions however.

Test Plan: Nada, commit is fine on it's own.

Reviewers: Mustaavalkosta, michyprima, rlasalle15, randall.rushing

Differential Revision: http://review.codefirex.com/D193

Change-Id: I151d65dc576290adea3062eab0536cb672139190