De-inline ~QDeviceClosedNotifier

This is weird, since Clang -Wweak-table didn't trigger here.

But -Wmarc did...

That's because the virtual functions behind the Q_OBJECT macro are
implemented in the moc file, so are actually out-of-line. And
~QObject() isn't the first virtual function in QObject...

Still define the destructor out-of-line, for consistency.

Amends ad265c55be.

Task-number: QTBUG-45582
Task-number: QTBUG-126219
Change-Id: Iada95966b7244873390f4c7ad42de9352311ca33
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 41c5856ffa6cac43c15a6a43261b6693e7b0566f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/serialization/qtextstream.cpp

@@ -249,6 +249,11 @@ QT_BEGIN_NAMESPACE
 using namespace Qt::StringLiterals;
 using namespace QtMiscUtils;
 
+#ifndef QT_NO_QOBJECT
+QDeviceClosedNotifier::~QDeviceClosedNotifier()
+    = default;
+#endif
+
 //-------------------------------------------------------------------
 
 /*!

src/corelib/serialization/qtextstream_p.h

@@ -31,6 +31,7 @@ class QDeviceClosedNotifier : public QObject
 public:
     inline QDeviceClosedNotifier()
     { }
+    ~QDeviceClosedNotifier() override;
 
     inline void setupDevice(QTextStream *stream, QIODevice *device)
     {