[sledge] Clear terminal between builds in watch mode
[sledge] Clear terminal between builds in watch mode

Summary:
Otherwise it is difficult to tell the difference between compilation
errors from previous versus current builds.

Reviewed By: ngorogiannis

Differential Revision: D18736376

fbshipit-source-id: 2e583f4ba

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