Fix another case of undefined behaviour

(cherry picked from commit 20e7ea1336)

kdecore/network/kresolverworkerbase.cpp

@@ -140,6 +140,14 @@ void KResolverWorkerBase::releaseResolver()
   th->releaseResolver();
 }
 
+KResolverWorkerFactoryBase::KResolverWorkerFactoryBase()
+{
+}
+
+KResolverWorkerFactoryBase::~KResolverWorkerFactoryBase()
+{
+}
+
 void KResolverWorkerFactoryBase::registerNewWorker(KResolverWorkerFactoryBase* factory)
 {
   KResolverManager::manager()->registerNewWorker(factory);

kdecore/network/kresolverworkerbase.h

@@ -289,6 +289,12 @@ protected:
 class KResolverWorkerFactoryBase
 {
 public:
+  // default constructor
+  KResolverWorkerFactoryBase();
+
+  // virtual destructor
+  virtual ~KResolverWorkerFactoryBase();
+
   virtual KResolverWorkerBase* create() const = 0;
 
   /**