refactor coroutine lowering and tasks

src/runtime/scheduler_none.go

@@ -0,0 +1,14 @@
+// +build scheduler.none
+
+package runtime
+
+//go:linkname sleep time.Sleep
+func sleep(duration int64) {
+	sleepTicks(timeUnit(duration / tickMicros))
+}
+
+// getSystemStackPointer returns the current stack pointer of the system stack.
+// This is always the current stack pointer.
+func getSystemStackPointer() uintptr {
+	return getCurrentStackPointer()
+}