New scheduler and interruptible blocking.

A new scheduler replaces the old one.
  - There are no sched_xxx_notify() calls that ask scheduler to change task state.
  - Tasks now have priorities and different timeslices.
  - One second interval is distributed among processes.
  - There are just runnable and expired queues.
  - SCHED_GRANULARITY determines a maximum running boundary for tasks.
  - Scheduler can now detect a safe point and suspend a task.

Interruptible blocking is implemented.
  - Mutexes, waitqueues and ipc are modified to have an interruptible nature.
  - Sleep information is stored on the ktcb. (which waitqueue? etc.)

include/l4/lib/mutex.h

@@ -16,20 +16,18 @@
 
 /* A mutex is a binary semaphore that can sleep. */
 struct mutex {
-	int sleepers;			/* Number of sleepers */
-	struct spinlock slock;		/* Locks sleeper queue */
-	unsigned int lock;		/* The mutex lock itself */
-	struct waitqueue wq;		/* Sleeper queue head */
+	struct waitqueue_head wqh;
+	unsigned int lock;
 };
 
 static inline void mutex_init(struct mutex *mutex)
 {
 	memset(mutex, 0, sizeof(struct mutex));
-	INIT_LIST_HEAD(&mutex->wq.task_list);
+	waitqueue_head_init(&mutex->wqh);
 }
 
 int mutex_trylock(struct mutex *mutex);
-void mutex_lock(struct mutex *mutex);
+int mutex_lock(struct mutex *mutex);
 void mutex_unlock(struct mutex *mutex);
 
 /* NOTE: Since spinlocks guard mutex acquiring & sleeping, no locks needed */