test_task: Use qi::Atomic to fix a 'counter++' race.
test_task: Use qi::Atomic to fix a 'counter++' race.

Change-Id: Id71a838c61634dddcd5f9e1d5584bfef8b0dd064
Reviewed-on: http://gerrit.aldebaran.lan/25281
Reviewed-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>
Tested-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>

aldebaran/libqi,aldebaran/libqi,bsautron/libqi,aldebaran/libqi,vbarbaresi/libqi