[sledge] Fix Solver tracing
[sledge] Fix Solver tracing

Reviewed By: ngorogiannis

Differential Revision: D20120273

fbshipit-source-id: b84e885ab

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