up to 5.3.21

up to 5.3.21

17-January-2013
* Zend Engine:
- Fixed bug #63762 (Sigsegv when Exception::$trace is changed by user).

* cURL extension:
- Fixed bug (segfault due to libcurl connection caching).
- Fixed bug #63795 (CURL >= 7.28.0 no longer support value 1 for CURLOPT_SSL_VERIFYHOST).
- Fixed bug #63352 (Can't enable hostname validation when using curl stream wrappers).
- Fixed bug #55438 (Curlwapper is not sending http header randomly).