Revert "Fix bug #67644 - Memory corruption & crash during ob_start function callback"

This reverts commit 53fa6c5b6b5b09059ba54c8912d0c0aef57aa4ff.
The change breaks tests, so not putting it into 5.4.
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  Revert "Fix bug #67644 - Memory corruption & crash during ob_start function callback"