package/php: security bump version to 5.6.18

Changelog: http://www.php.net/ChangeLog-5.php#5.6.18
Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Acked-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/php/php.hash

@@ -1,2 +1,2 @@
 # From http://php.net/downloads.php
-sha256	ea9d5749380c7c7171e131616466deacd7cb124b5010eafc34e551b0a7b0fb2c	php-5.6.17.tar.xz
+sha256	54dd9106c3469bc7028644d72ac140af00655420bbaaf4a742a64e9ed02ec1b0	php-5.6.18.tar.xz

package/php/php.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-PHP_VERSION = 5.6.17
+PHP_VERSION = 5.6.18
 PHP_SITE = http://www.php.net/distributions
 PHP_SOURCE = php-$(PHP_VERSION).tar.xz
 PHP_INSTALL_STAGING = YES