Add WIN_VCARD to win_get_tab_identifier()

Thanks to 12b997c5f3 we already found a
place where we should add this missing window type.
AFAIK there can be only one vcard window.

src/ui/window.c

@@ -433,6 +433,10 @@ win_get_tab_identifier(ProfWin* window)
     {
         return strdup("xmlconsole");
     }
+    case WIN_VCARD:
+    {
+        return strdup("vcard");
+    }
     }
     assert(FALSE);
 }