Re-fix Bug #65372 (Segfault in gc_zval_possible_root when return reference fails)

Missed a zval_copy_ctor there
Merge branch 'PHP-5.4' of https://git.php.net/repository/php-src into PHP-5.4

# By Xinchen Hui
# Via Xinchen Hui
* 'PHP-5.4' of https://git.php.net/repository/php-src:
  Re-fix Bug #65372 (Segfault in gc_zval_possible_root when return reference fails)