QInputDeviceManager: ++explicit, ++out-of-line-dtors

It's private API, but exported, so de-inline the dtor to pin the
vtable in QtCore instead of potentially duplicating it in every plugin
that uses the class.

Change-Id: Ia948985bb94677c8453a8e7be27a14085303aaf5
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

src/gui/kernel/qinputdevicemanager.cpp

@@ -67,6 +67,8 @@ QInputDeviceManager::QInputDeviceManager(QObject *parent)
     qRegisterMetaType<DeviceType>();
 }
 
+QInputDeviceManager::~QInputDeviceManager() = default;
+
 int QInputDeviceManager::deviceCount(DeviceType type) const
 {
     Q_D(const QInputDeviceManager);

src/gui/kernel/qinputdevicemanager_p.h

@@ -74,7 +74,8 @@ public:
         NumDeviceTypes
     };
 
-    QInputDeviceManager(QObject *parent = nullptr);
+    explicit QInputDeviceManager(QObject *parent = nullptr);
+    ~QInputDeviceManager() override;
 
     int deviceCount(DeviceType type) const;