kernel: refactor syscall dispatch system

syscall/task.c

@@ -0,0 +1,13 @@
+#include <mango/machine/cpu.h>
+#include <mango/printk.h>
+#include <mango/sched.h>
+
+extern kern_status_t sys_exit(int status)
+{
+	printk("sys_exit(%d)", status);
+	while (1) {
+		ml_cpu_pause();
+	}
+
+	return KERN_UNIMPLEMENTED;
+}