Fix another case of undefined behaviour

diff --git a/tdecore/network/kresolverworkerbase.cpp b/tdecore/network/kresolverworkerbase.cpp
index ee6ee10..f149e2d 100644
--- a/tdecore/network/kresolverworkerbase.cpp
+++ b/tdecore/network/kresolverworkerbase.cpp
@@ -140,6 +140,14 @@
   th->releaseResolver();
 }
 
+KResolverWorkerFactoryBase::KResolverWorkerFactoryBase()
+{
+}
+
+KResolverWorkerFactoryBase::~KResolverWorkerFactoryBase()
+{
+}
+
 void KResolverWorkerFactoryBase::registerNewWorker(KResolverWorkerFactoryBase* factory)
 {
   KResolverManager::manager()->registerNewWorker(factory);
diff --git a/tdecore/network/kresolverworkerbase.h b/tdecore/network/kresolverworkerbase.h
index 4dee332..e0a676c 100644
--- a/tdecore/network/kresolverworkerbase.h
+++ b/tdecore/network/kresolverworkerbase.h
@@ -289,6 +289,12 @@
 class KResolverWorkerFactoryBase
 {
 public:
+  // default constructor
+  KResolverWorkerFactoryBase();
+
+  // virtual destructor
+  virtual ~KResolverWorkerFactoryBase();
+
   virtual KResolverWorkerBase* create() const = 0;
 
   /**