[sledge] Factor solve_poly_eq out of solve_interp_eq
[sledge] Factor solve_poly_eq out of solve_interp_eq

Reviewed By: ngorogiannis

Differential Revision: D19356326

fbshipit-source-id: 3873476d5

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