notify: fix prevent issue, dereference null return value

Summary: Fix prevent issue: Dereference null return value

Test Plan: Use static analysis tool such as prevent

Reviewers: raster, woohyun, jaehwan, Hermet

Subscribers: seoz

Differential Revision: https://phab.enlightenment.org/D2669

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

legacy/elementary/src/lib/elm_sys_notify.c

@@ -257,6 +257,11 @@ _on_action_invoked(void *data EINA_UNUSED,
      }
 
    d = calloc(1, sizeof(*d));
+   if (!d)
+     {
+        ERR("Fail to allocate memory");
+        return;
+     }
 
    if (!eldbus_message_arguments_get(msg, "us", &(d->id), &aux))
      {