[reactive] always delete specs dir
[reactive] always delete specs dir

Summary:
Specs do not get invalidated by reactive mode, so we need to delete them all.
Reactive just means that the capture remains valid and the analysis will only
use the freshly captured source files to start the analysis, but all the
dependencies will be re-analysed.

Reviewed By: da319

Differential Revision: D8735171

fbshipit-source-id: dc1eab3

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