Assert that there is at most one flowgraph per procedure name.
Assert that there is at most one flowgraph per procedure name.

Reviewed By: jvillard

Differential Revision: D15695839

fbshipit-source-id: 979531edb

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