ProjectExplorer: Use a data member for BuildStep::runInGuiThread

Change-Id: Ia219fcf595c05c6f1b82f420454bd906c6870ee7
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/ios/iosdeploystep.cpp

@@ -60,6 +60,7 @@ IosDeployStep::IosDeployStep(BuildStepList *parent)
     : BuildStep(parent, Id)
 {
     setImmutable(true);
+    setRunInGuiThread(true);
     updateDisplayNames();
     connect(DeviceManager::instance(), &DeviceManager::updated,
             this, &IosDeployStep::updateDisplayNames);