Clock task split

- preemption handled in the clock timer interrupt handler, not in the clock task

- more achitecture independent clock timer handling code

- smp ready as each CPU can have its own timer

kernel/clock.h

@@ -0,0 +1,16 @@
+#ifndef __CLOCK_H__
+#define __CLOCK_H__
+
+#include "kernel.h"
+#include "arch/i386/clock.h"
+
+_PROTOTYPE(int boot_cpu_init_timer, (unsigned freq));
+
+_PROTOTYPE(int bsp_timer_int_handler, (void));
+_PROTOTYPE(int ap_timer_int_handler, (void));
+
+_PROTOTYPE(int arch_init_local_timer, (unsigned freq));
+_PROTOTYPE(void arch_stop_local_timer, (void));
+_PROTOTYPE(int arch_register_local_timer_handler, (irq_handler_t handler));
+
+#endif /* __CLOCK_H__ */