QAdoptedThread: bypass signal notification on an un-observable QObject

We've just created the object (we're still inside the constructor). No
one can have connected to the signals yet.

Change-Id: I1f499b3fc6d2089665bdfffda709e1efaa2c4865
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

src/corelib/kernel/qobject.cpp

@@ -1288,6 +1288,17 @@ QString QObject::objectName() const
     return d->extraData ? d->extraData->objectName : QString();
 }
 
+/*!
+    \internal
+    Only use if you know nothing can be bound yet. Usually used for
+    internal objects that do get names.
+*/
+void QObjectPrivate::setObjectNameWithoutBindings(const QString &name)
+{
+    ensureExtraData();
+    extraData->objectName.setValueBypassingBindings(name);
+}
+
 /*!
     \fn void QObject::setObjectName(const QString &name)
     Sets the object's name to \a name.

src/corelib/kernel/qobject_p.h

@@ -104,6 +104,7 @@ public:
         if (!extraData)
             extraData = new ExtraData(this);
     }
+    void setObjectNameWithoutBindings(const QString &name);
 
     typedef void (*StaticMetaCallFunction)(QObject *, QMetaObject::Call, int, void **);
     struct Connection;

src/corelib/thread/qthread.cpp

@@ -126,7 +126,9 @@ QAdoptedThread::QAdoptedThread(QThreadData *data)
         // we are the main thread
         QCoreApplicationPrivate::theMainThread.storeRelease(this);
         QCoreApplicationPrivate::theMainThreadId.storeRelaxed(id);
-        setObjectName(u"Qt mainThread"_s);
+
+        // bypass the bindings because nothing can be listening yet
+        d_func()->setObjectNameWithoutBindings(u"Qt mainThread"_s);
     }
 
     // thread should be running and not finished for the lifetime