friendica-addons/facebook_restrict/facebook_restrict.php

<?php

/**
 * Name: Facebook Restrict
 * Description: Install this addon and Facebook users will not be able to link friends. Existing users that are linking friends will not be affected.
 * Version: 1.0
 * Author: Mike Macgirvin <http://macgirvin.com/profile/mike>
 * Status: Unsupported
 */


function facebook_restrict_install() {
	set_config('facebook','restrict',1);
}

function facebook_restrict_uninstall() {
	set_config('facebook','restrict',0);
}