Added different paths of exiting for pager and its children.

Created a task_dead list on pager for children to move to when
they exit.

include/l4/generic/tcb.h

@@ -80,6 +80,7 @@ struct ktcb {
 	enum task_state state;
 
 	struct link task_list; /* Global task list. */
+	struct ktcb_list task_dead; /* List of dead children */
 
 	/* UTCB related, see utcb.txt in docs */
 	unsigned long utcb_address;	/* Virtual ref to task's utcb area */