php: security bump to version 5.6.11

Fixes:
CVE-2015-3152 - mysqlnd is vulnerable to BACKRONYM

And other security bugs with no CVE assigned yet:
Bug #69972 - Use-after-free vulnerability in
sqlite3SafetyCheckSickOrOk()
Bug # 69970 - Use-after-free vulnerability in
spl_recursive_it_move_forward_ex()

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