scheduler: properly open init cwd and root, sched_dequeue()

src/include/kernel/sched.h

@@ -67,6 +67,8 @@ typedef struct{
 	int lock;
 } sched_queue;
 
+void sched_dequeue();
+proc_t* sched_getinit();
 thread_t* sched_newuthread(void* ip, size_t stacksize, void* stack, proc_t* proc, bool run, int prio);
 thread_t* sched_newkthread(void* ip, size_t stacksize, bool run, int prio);
 void sched_queuethread(thread_t* thread);