Promise: fix a data race in Promise::setup
Promise: fix a data race in Promise::setup

Data race between Promise::setup and Future::finish
reported by TSan.

Change-Id: I54c64c82e58fb8a4938bbe4c3002ff655713a6a3
Reviewed-on: http://gerrit.aldebaran.lan/83323
Reviewed-by: vincent.palancher <f8ff75e1c61314c499fafa8de0d9e004e87e66b0@external.softbankrobotics.com>
Reviewed-by: jlamotte <70353e7b0c7d18b7fc75605daf0ccba69fcd3222@aldebaran.com>
Tested-by: vincent.palancher <f8ff75e1c61314c499fafa8de0d9e004e87e66b0@external.softbankrobotics.com>

aldebaran/libqi,aldebaran/libqi,aldebaran/libqi