enforce border_fix_on_shelf_toggle config option in shelf

shelf overlap can only take effect based on the state of this option:
specifically, overlap can only be enabled if border_fix_on_shelf_toggle
is enabled

src/bin/e_shelf.c

@@ -91,7 +91,7 @@ _e_shelf_remaximize(E_Shelf *es)
 {
    E_Client *ec;
 
-   if (es->cfg->overlap) return;
+   if (es->cfg->overlap && e_config->border_fix_on_shelf_toggle) return;
    E_CLIENT_FOREACH(ec)
      {
         E_Maximize max = ec->maximized;