fix(fastcgi): fix symlink support in fastcgi FILENAME param

Author: tntrex

spaceonfire/presets/default/nginx/vhost.common.d/20-php.conf

@@ -3,7 +3,8 @@ location ~ \.php$ {
 	try_files $uri =404;
 	fastcgi_split_path_info ^(.+\.php)(/.+)$;
 	fastcgi_pass php-upstream;
-	fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
+	fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;
+	fastcgi_param DOCUMENT_ROOT $realpath_root;
 	fastcgi_param SCRIPT_NAME $fastcgi_script_name;
 	fastcgi_index index.php;
 	include fastcgi_params;