Added support for faulty pagers and their threads to become zombies

Added support for pagers that fault to suspend and become zombies
along with all the threads that they manage. Zombie killing is to
be done at a later time, from this special zombie queue.

The implementation works same as a suspension, with the added action
that the thread is moved to a queue in kernel container.

src/generic/scheduler.c

@@ -14,6 +14,7 @@
 #include <l4/generic/resource.h>
 #include <l4/generic/container.h>
 #include <l4/generic/preempt.h>
+#include <l4/generic/thread.h>
 #include <l4/generic/irq.h>
 #include <l4/generic/tcb.h>
 #include <l4/api/errno.h>
@@ -239,6 +240,9 @@ void sched_suspend_sync(void)
 	BUG_ON(scheduler.prio_total < 0);
 	preempt_enable();
 
+	if (current->flags & TASK_EXITING)
+		thread_make_zombie(current);
+
 	/*
 	 * Async wake up any waiting pagers
 	 *