elmentary: prevent crash in multibuttonentry.

Summary: Do Null checking to prevent crash, if 'elm_object_text_get()' return NULL here.

Reviewers: Hermet, woohyun, jpeg, cedric

Subscribers: cedric, jpeg

Differential Revision: https://phab.enlightenment.org/D4501

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

src/lib/elementary/elc_multibuttonentry.c

@@ -1179,6 +1179,7 @@ _entry_key_up_cb(void *data,
    if (!sd->box) return;
 
    str = elm_object_text_get(sd->entry);
+   if (!str) return;
 
    if (strlen(str) &&
        (!strcmp(ev->key, "KP_Enter") || !strcmp(ev->key, "Return")))