Log Message:
update php-xdebug to version 2.4.0

Added features:
- Implemented issue #1109: Added support for PHP 7.
- Implemented issue #1153: Add function monitor functionality.
- Implemented issue #1183: Add xdebug.show_error_trace setting to
allow/disallow to show a stack trace for every Error (throwable)

Besides this, many bugfixes