Do not send task bar updates when progress bar is off

Summary: When the progress bar was off (`--no-progress-bar`) the `TaskBar` didn't log updates but the workers still sent them to the master process. Now, the workers no longer send updates to the master process when the progress bar is off.

Reviewed By: ngorogiannis

Differential Revision: D20140577

fbshipit-source-id: 560d56991

infer/src/base/ProcessPool.ml

@@ -391,6 +391,10 @@ let fork_child ~file_lock ~child_prelude ~slot (updates_r, updates_w) ~f ~epilog
          bar. This is because only the parent knows about all the children, hence it's in charge of
          actually updating the task bar. *)
       let update_status t status =
+        match Config.progress_bar with
+        | `Quiet | `Plain ->
+            ()
+        | `MultiLine ->
             let status =
               (* Truncate status if too big: it's pointless to spam the status bar with long status, and
                  also difficult to achieve technically over pipes (it's easier if all the messages fit