[short review] Add logging for when the results directory is deleted

Summary:
Incremental analysis isn't behaving as expected in production, and I think the deletion and re-creation of the results directory is why

Adding logging to test this theory

Reviewed By: ngorogiannis

Differential Revision: D16730426

fbshipit-source-id: 0a670cabf

infer/src/infer.ml

@@ -43,7 +43,9 @@ let setup () =
              || Config.(
                   continue_capture || infer_is_clang || infer_is_javac || reactive_mode
                   || incremental_analysis) )
-      then ResultsDir.remove_results_dir () ;
+      then (
+        L.progress "Cleaning results directory@." ;
+        ResultsDir.remove_results_dir () ) ;
       ResultsDir.create_results_dir () ;
       if
         CLOpt.is_originator && (not Config.continue_capture)