elm_ctxpopup: prevent a giant load of errors

elm_ctxpopup: prevent a giant load of errors

Summary:
i)  There have been 2 sorts of errors, first the items have been deleted
    after the list was deleted, thus the list items have already been
    destructed. which lead to the error as the popup items destroyed the list
    items on destruction as well.

ii) sd->box was attached to the ctxpopup when getting into group_del the
    box has already been destroyed by the cleanup logic.

Subscribers: cedric, zmike

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D6166

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