add special case for returning pixmap argb of unusable wl cursor pixmaps

this is usually called before the surface commits, so ensure that the
most likely case is returned as the default until the commit occurs

fixes black rect flickerings around the cursor

src/bin/e_pixmap.c

@@ -899,7 +899,10 @@ e_pixmap_image_is_argb(const E_Pixmap *cp)
 #endif
       case E_PIXMAP_TYPE_WL:
 #ifdef HAVE_WAYLAND
-        return cp->image_argb;
+        if (cp->usable)
+          return cp->image_argb;
+        if (((E_Comp_Wl_Client_Data*)cp->client->comp_data)->cursor)
+          return EINA_TRUE;
 #endif
         default: break;
      }