ecore_evas: Check for null ptr deref

Summary:
This patch fixes a tentative crash owing to ptr dereference.
Unlike ecore_evas_object_cursor_set and ecore_evas_object_cursor_device_set,
ecore_evas_cursor_set uses Ecore_Evas *ee before calling internal function which
internally checks null ptr dereference of Ecore_Evas *ee.

Test Plan: Executes test suite

Reviewers: cedric, raster, stefan, Jaehyun_Cho

Reviewed By: Jaehyun_Cho

Subscribers: jpeg

Differential Revision: https://phab.enlightenment.org/D5753

src/lib/ecore_evas/ecore_evas.c

@@ -1832,6 +1832,9 @@ ecore_evas_cursor_set(Ecore_Evas *ee, const char *file,
                       int layer, int hot_x, int hot_y)
 {
    Evas_Object *obj = NULL;
+
+   ECORE_EVAS_CHECK(ee);
+
    if (file)
      {
         int x, y;