mention the changes regarding ReflectionClass::newInstanceWithoutConstructor in UPGRADING
see the discussion on the mailing list and in the pull request for details:
https://github.com/php/php-src/pull/733
Merge branch 'PHP-5.6'

* PHP-5.6:
  mention the changes regarding ReflectionClass::newInstanceWithoutConstructor in UPGRADING see the discussion on the mailing list and in the pull request for details: https://github.com/php/php-src/pull/733