QDtls and QDtlsClientVerifier - add destructors

While these destructors are essentially trivial and contain no code,
the classes inherit QObject and thus have virtual tables. For such
classes -Wweak-vtable generates a warning: "'Class' has no out-of-line
virtual method definitions; its vtable will be emitted in every translation
unit." Noticed this after updating QtCreator to the latest version.

Change-Id: Iacb5d0cd49353bd35260aff736652542bb1ef197
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/ssl/qdtls.cpp

@@ -453,6 +453,13 @@ QDtlsClientVerifier::QDtlsClientVerifier(QObject *parent)
     d->setConfiguration(conf);
 }
 
+/*!
+    Destroys the QDtlsClientVerifier object.
+*/
+QDtlsClientVerifier::~QDtlsClientVerifier()
+{
+}
+
 /*!
     Sets the secret and the cryptographic hash algorithm from \a params. This
     QDtlsClientVerifier will use these to generate cookies. If the new secret
@@ -576,6 +583,13 @@ QDtls::QDtls(QSslSocket::SslMode mode, QObject *parent)
     setDtlsConfiguration(QSslConfiguration::defaultDtlsConfiguration());
 }
 
+/*!
+    Destroys the QDtls object.
+*/
+QDtls::~QDtls()
+{
+}
+
 /*!
     Sets the peer's address, \a port, and host name and returns \c true
     if successful. \a address must not be null, multicast, or broadcast.

src/network/ssl/qdtls.h

@@ -78,6 +78,7 @@ class Q_NETWORK_EXPORT QDtlsClientVerifier : public QObject
 public:
 
     explicit QDtlsClientVerifier(QObject *parent = nullptr);
+    ~QDtlsClientVerifier();
 
     struct Q_NETWORK_EXPORT GeneratorParameters
     {
@@ -125,6 +126,7 @@ public:
     };
 
     explicit QDtls(QSslSocket::SslMode mode, QObject *parent = nullptr);
+    ~QDtls();
 
     bool setPeer(const QHostAddress &address, quint16 port,
                  const QString &verificationName = {});