Summary:
First steps towards implementing diff analysis functionalities inside infer
itself. What works: run infer, checkout parent, re-run infer, checkout top
revision, compute the reportdiff (but no final surfacing on the console). Lots
of TODO still, inlined in the code.
Reviewed By: jberdine
Differential Revision: D5364226
fbshipit-source-id: 5b7f9a5