Eio_monitor: support native monitor for Win32 (T4978)

Test Plan:
eio_monitor_backend_add()  and eio_monitor_fallback_add use different structures
**eio_monitor_backend_add()  **
struct _Eio_Monitor_Backend
{
   Eio_Monitor               *parent;
   Eio_Monitor_Win32_Watcher *watcher_file;
   Eio_Monitor_Win32_Watcher *watcher_dir;
   Eio_Monitor_Win32_Watcher *watcher_parent;
};

**eio_monitor_fallback_add()**
struct _Eio_Monitor_Backend
{
   Eio_Monitor *parent;

   Eina_Stat self;
   Eina_Hash *children;

   Ecore_Timer *timer;
   Ecore_Idler *idler;
   Ecore_Thread *work;

   int version;

   Eina_Bool delete_me : 1;
   Eina_Bool initialised : 1;
   Eina_Bool destroyed : 1;
};

therefore, an error occurs
**void eio_monitor_backend_del**(Eio_Monitor *monitor)
{

   if (!_eio_monitor_win32_native)          <------_eio_monitor_win32_native is EINA_TRUE
     {

        eio_monitor_fallback_del(monitor);  <------ignored------
        return;                             <------ignored------
     }

   _eio_monitor_win32_watcher_free(monitor->backend->watcher_parent);
   _eio_monitor_win32_watcher_free(monitor->backend->watcher_dir);
   _eio_monitor_win32_watcher_free(monitor->backend->watcher_file);
   free(monitor->backend);
   monitor->backend = NULL;
}

Reviewers: raster, vtorri, an.kroitor, jpeg, reutskiy.v.v, FurryMyad, cedric

Reviewed By: cedric

Subscribers: vtorri, artem.popov, cedric, jpeg

Tags: #windows, #efl

Differential Revision: https://phab.enlightenment.org/D4492

Signed-off-by: Cedric BAIL <cedric@osg.samsung.com>

src/lib/eio/eio_monitor_win32.c

@@ -418,6 +418,7 @@ void eio_monitor_backend_add(Eio_Monitor *monitor)
    free(backend);
  fallback:
    INF("falling back to poll monitoring");
+   _eio_monitor_win32_native = EINA_FALSE;
    eio_monitor_fallback_add(monitor);
 }