Fix "Undefined variable $url_search"

Whoops\Exception\ErrorException thrown with message "Undefined variable $url_search"

Stacktrace:
#4 Whoops\Exception\ErrorException in /var/www/enginegp/data/www/demo.enginegp.com/system/acp/sections/control/index.php:49
#3 Whoops\Run:handleError in /var/www/enginegp/data/www/demo.enginegp.com/system/acp/sections/control/index.php:49
#2 include in /var/www/enginegp/data/www/demo.enginegp.com/system/acp/engine/control.php:36
#1 include in /var/www/enginegp/data/www/demo.enginegp.com/system/acp/distributor.php:63
#0 include in /var/www/enginegp/data/www/demo.enginegp.com/acp/index.php:50

system/acp/sections/control/index.php

@@ -46,6 +46,7 @@ else {
 
     $html->get('index', 'sections/control');
     $html->set('list', $list);
+    $url_search = isset($url['search']) ? $url['search'] : '';
     $html->set('url_search', $url_search);
     $html->set('pages', isset($html->arr['pages']) ? $html->arr['pages'] : '');
     $html->pack('main');