Elm entry: fix null item in item provider.

Item anchors can have null items likes <item size=10x10>. That is,
there is no "href". The problem is that Elm Entry segfaults as it
expects a non-null item. I prefer this fix over passing "" from Edje
Entry, and leave the decision to be made by Elm Entry. It will now just
show the error emoticon if there is no "href".

@fix

legacy/elementary/src/lib/elm_entry.c

@@ -2563,7 +2563,7 @@ _item_get(void *data,
         o = ip->func(ip->data, data, item);
         if (o) return o;
      }
-   if (!strncmp(item, "file://", 7))
+   if (item && !strncmp(item, "file://", 7))
      {
         const char *fname = item + 7;