php: add FPM support

[Thomas: adjust commit title, as suggested by Gustavo.]

Signed-off-by: Jordi Llonch <jordi.llonch@rochsystems.com>
Acked-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>