facebook/hhvm — pull request #4414 by reeze (2014-12-09 15:02:43+00:00)
Title: Fix error_get_last() not cleared when error handle function entered

This also :
- make get_last_error() not available in error handler like
PHP, see http://3v4l.org/QKQKY
- clear last error when request shutdown, prevent errmessage
leak to the next request

Closes #4407