QHostInfo: de-inline -Result and -Runnable dtors

These classes are not exported, so we don't run into duplicate vtables
here, but the header is included in a few TUs other than qhostinfo.cpp
(all, when building with PCH), so make sure we compile dtors only once.

Change-Id: I51f6a6d27fc084ad469f82dc7aef3327bdd9a906
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
(cherry picked from commit a2c8524ad7dd59f31b400b5da8979138dc835fcc)
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/network/kernel/qhostinfo.cpp

@@ -72,6 +72,9 @@ Q_APPLICATION_STATIC(QHostInfoLookupManager, theHostInfoLookupManager)
 
 }
 
+QHostInfoResult::~QHostInfoResult()
+    = default;
+
 /*
     The calling thread is likely the one that executes the lookup via
     QHostInfoRunnable. Unless we operate with a queued connection already,
@@ -818,6 +821,9 @@ QHostInfoRunnable::QHostInfoRunnable(const QString &hn, int i, const QObject *re
     setAutoDelete(true);
 }
 
+QHostInfoRunnable::~QHostInfoRunnable()
+    = default;
+
 // the QHostInfoLookupManager will at some point call this via a QThreadPool
 void QHostInfoRunnable::run()
 {

src/network/kernel/qhostinfo_p.h

@@ -51,6 +51,8 @@ public:
             moveToThread(receiver->thread());
     }
 
+    ~QHostInfoResult() override;
+
     void postResultsReady(const QHostInfo &info);
 
 Q_SIGNALS:
@@ -143,6 +145,8 @@ class QHostInfoRunnable : public QRunnable
 public:
     QHostInfoRunnable(const QString &hn, int i, const QObject *receiver,
                       QtPrivate::QSlotObjectBase *slotObj);
+    ~QHostInfoRunnable() override;
+
     void run() override;
 
     QString toBeLookedUp;