Fixed set_country_vars() duplicate declaration issue during domain creation

app/vars/app_defaults.php

@@ -73,6 +73,7 @@ $vars = <<<EOD
 EOD;
 
 // Set country depend variables as country code and international direct dialing code (exit code)
+	if (!function_exists('set_country_vars')) {
 		function set_country_vars($db, $x) {
 
 			$country_list = <<<EOD
@@ -458,6 +459,7 @@ EOD;
 
 			unset($countries);				
 		}
+	}
 
 	$x = 1;