Added WaitObjectListener destructor. Hopefully fixes the gcc 2 build.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30346 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/listeners.h

@@ -68,6 +68,8 @@ NotifySchedulerListeners(
 
 
 struct WaitObjectListener : DoublyLinkedListLinkImpl<WaitObjectListener> {
+	virtual						~WaitObjectListener();
+
 	virtual	void				SemaphoreCreated(sem_id id,
 									const char* name) = 0;
 	virtual	void				ConditionVariableInitialized(

src/system/kernel/listeners.cpp

@@ -10,6 +10,11 @@ WaitObjectListenerList gWaitObjectListeners;
 spinlock gWaitObjectListenerLock = B_SPINLOCK_INITIALIZER;
 
 
+WaitObjectListener::~WaitObjectListener()
+{
+}
+
+
 /*!	Add the given wait object listener. gWaitObjectListenerLock lock must be
 	held.
 */