Update php55 to 5.5.20, including security fix.

17 Dec 2014, PHP 5.5.20

- Core:
  . Fixed bug #68091 (Some Zend headers lack appropriate extern "C" blocks).
    (Adam)
  . Fixed bug #68185 ("Inconsistent insteadof definition."- incorrectly
    triggered). (Julien)
  . Fixed bug #68370 ("unset($this)" can make the program crash). (Laruence)
  . Fixed bug #68545 (NULL pointer dereference in unserialize.c). (Anatol)
  . Fixed bug #68594 (Use after free vulnerability in unserialize()).
    (CVE-2014-8142) (Stefan Esser)

- Date:
  . Fixed day_of_week function as it could sometimes return negative values
    internally. (Derick)

- FPM:
  . Fixed bug #68381 (fpm_unix_init_main ignores log_level).
    (David Zuelke, Remi)
  . Fixed bug #68420 (listen=9000 listens to ipv6 localhost instead of all
    addresses). (Remi)
  . Fixed bug #68421 (access.format='%R' doesn't log ipv6 address). (Remi)
  . Fixed bug #68423 (PHP-FPM will no longer load all pools). (Remi)
  . Fixed bug #68428 (listen.allowed_clients is IPv4 only). (Remi)
  . Fixed bug #68452 (php-fpm man page is oudated). (Remi)
  . Fixed request #68458 (Change pm.start_servers default warning to
    notice). (David Zuelke, Remi)
  . Fixed bug #68463 (listen.allowed_clients can silently result
    in no allowed access). (Remi)
  . Fixed request #68391 (php-fpm conf files loading order).
    (Florian Margaine, Remi)
  . Fixed bug #68478 (access.log don't use prefix). (Remi)

- Mcrypt:
  . Fixed possible read after end of buffer and use after free. (Dmitry)

- PDO_pgsql:
  . Fixed bug #66584 (Segmentation fault on statement deallocation) (Matteo)
  . Fixed bug #67462 (PDO_PGSQL::beginTransaction() wrongly throws exception
  when not in transaction) (Matteo)
  . Fixed bug #68351 (PDO::PARAM_BOOL and ATTR_EMULATE_PREPARES misbehaving)
  (Matteo)

- zlib:
  . Fixed bug #53829 (Compiling PHP with large file support will replace
    function gzopen by gzopen64) (Sascha Kettler, Matteo)

(taca)