hw: clean-up destruction of processor clients

ref #1088

base-hw/src/core/kernel/kernel.cc

@@ -315,9 +315,6 @@ Kernel::Mode_transition_control * Kernel::mtc()
 }
 
 
-Kernel::Processor_client::~Processor_client() { }
-
-
 Kernel::Cpu_context::Cpu_context()
 {
 	_init(STACK_SIZE);

base-hw/src/core/kernel/scheduler.h

@@ -73,19 +73,19 @@ class Kernel::Double_list_item
 		Double_list_item * _prev;
 		Double_list<T> *   _list;
 
+	protected:
+
+		/**
+		 * Return wether this item is managed by a list currently
+		 */
+		bool _listed() const { return _list; }
+
 	public:
 
 		/**
 		 * Constructor
 		 */
 		Double_list_item() : _next(0), _prev(0), _list(0) { }
-
-
-		/***************
-		 ** Accessors **
-		 ***************/
-
-		Double_list<T> * list() { return _list; }
 };
 
 template <typename T>
@@ -217,6 +217,13 @@ class Kernel::Scheduler_item : public Double_list<T>::Item
 
 		Priority const _priority;
 
+	protected:
+
+		/**
+		 * Return wether this item is managed by a scheduler currently
+		 */
+		bool _scheduled() const { return Double_list<T>::Item::_listed(); }
+
 	public:
 
 		/**
@@ -370,7 +377,11 @@ class Kernel::Processor_client : public Processor_scheduler::Item
 		/**
 		 * Destructor
 		 */
-		virtual ~Processor_client();
+		~Processor_client()
+		{
+			if (!_scheduled()) { return; }
+			_unschedule();
+		}
 };
 
 #endif /* _KERNEL__SCHEDULER_H_ */

base-hw/src/core/kernel/thread.cc

@@ -189,8 +189,6 @@ Thread::Thread(unsigned const priority, char const * const label)
 	cpu_exception = RESET;
 }
 
-Thread::~Thread() { if (Processor_client::list()) { _unschedule(STOPPED); } }
-
 
 void
 Thread::init(Processor * const processor, unsigned const pd_id_arg,

base-hw/src/core/kernel/thread.h

@@ -298,11 +298,6 @@ class Kernel::Thread
 		 */
 		Thread(unsigned const priority, char const * const label);
 
-		/**
-		 * Destructor
-		 */
-		~Thread();
-
 		/**
 		 * Prepare thread to get scheduled the first time
 		 *