test_future: fix for new async cancel behavior

Change-Id: I9a058915218184f7ee3ad9f9f5498ad496f78564
ThreadPoolPrivate::waitForAll: while instead of if.

Change-Id: I36bc7518acb958e3228ec2299d4a2274965ebd3b
Reviewed-on: http://gerrit.aldebaran.lan:8080/15299
Reviewed-by: cgestes <gestes@aldebaran-robotics.com>
Reviewed-by: mnottale <mnottale@aldebaran-robotics.com>
Tested-by: mnottale <mnottale@aldebaran-robotics.com>
EventLoopThreadPool: safer teardown.

Change-Id: I21b5dd7ec82099ab3baee843cbd29e93a0c7f539
Reviewed-on: http://gerrit.aldebaran.lan:8080/15301
Tested-by: gerrit
Reviewed-by: cgestes <gestes@aldebaran-robotics.com>
Reviewed-by: mnottale <mnottale@aldebaran-robotics.com>
Tested-by: mnottale <mnottale@aldebaran-robotics.com>