buildroot

php: security bump to version 5.5.22

Fixes:
CVE-2015-0273 - Use after free vulnerability in unserialize() with
DateTimeZone.
CVE-2015-0235 - Mitigation for GHOST: glibc gethostbyname buffer
overflow.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>