ecore_wl2: Set the parent window's surface to NULL on surface destroy

Summary:
Prevents potential use after free.
Depends on D6277

Reviewers: devilhorns, zmike

Reviewed By: zmike

Subscribers: cedric, #committers, zmike

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D6278

src/lib/ecore_wl2/ecore_wl2_surface.c

@@ -17,6 +17,7 @@ ecore_wl2_surface_destroy(Ecore_Wl2_Surface *surface)
 
    ecore_event_handler_del(surface->offscreen_handler);
    surface->funcs->destroy(surface, surface->private_data);
+   surface->wl2_win->wl2_surface = NULL;
    surface->wl2_win = NULL;
 
    free(surface);