Add teardown function for the event.c module

Also move the `job_teardown` call from os_unix.c to the event module

src/os/event.c

@@ -41,6 +41,11 @@ void event_init()
   uv_prepare_init(uv_default_loop(), &timer_prepare);
 }
 
+void event_teardown()
+{
+  job_teardown();
+}
+
 // Wait for some event
 bool event_poll(int32_t ms)
 {