[sledge] Fix potential nontermination in concurrent scheduler
[sledge] Fix potential nontermination in concurrent scheduler

Summary:
There was a bug where the accumulator of the cursor through the
control successors was reset rather than accumulated.

Reviewed By: peterogithub

Differential Revision: D31129942

fbshipit-source-id: 8ef5c5626

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