It's accessed by QFutureWatcherBase::isFinished(), potentially before
anything has set it. It gets to be initially true until setFuture()
has given it us unfinished future and set it false.
Add a regression test for matching state in future and watcher.
Task-number: QTBUG-12358
Change-Id: Iae7bdaa434ab80f518afe4d7d55df99c391991a4
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@theqtcompany.com>