[lineage] More aggressive removal of temporaries
[lineage] More aggressive removal of temporaries

Summary:
It's OK to remove temps that are sources/sinks. A sink can occur, for
example, when you do `tmp=instanceof(a,T); prune(tmp)`, because `tmp` is
not used afterwards.

Reviewed By: thizanne

Differential Revision: D37718495

fbshipit-source-id: 1e3f80f58638128de0114501f7a2abb213c0d1ad

facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer