Silence code checker warning about unused std::unique_ptr::release

We don't need the pointer, as it's the same as "this", we just don't
want the event to own the object anymore.

Nevertheless, silence code checker warning about the unused return.

Amends 96ef000.

Change-Id: I6a3c73e971f1b9e10f5754018a1fa5941dca6172
Reviewed-by: Axel Spoerl <[email protected]>
(cherry picked from commit 920a490)
Reviewed-by: Volker Hilsheimer <[email protected]>
(cherry picked from commit bc2f4ac)
Reviewed-by: Qt Cherry-pick Bot <[email protected]>

Author: vohi

src/corelib/kernel/qsingleshottimer.cpp

@@ -76,7 +76,7 @@ void QSingleShotTimer::timerEvent(QTimerEvent *event)
 {
     if (event->id() == Qt::TimerId::Invalid) {
         StartTimerEvent *startTimerEvent = static_cast<StartTimerEvent *>(event);
-        startTimerEvent->timer.release();
+        Q_UNUSED(startTimerEvent->timer.release()); // it's the same as "this"
         const QDeadlineTimer &deadline = startTimerEvent->deadline;
         if (deadline.hasExpired()) {
             timerFinished();