postgresql: security bump to 9.6.8

Helps mitigate CVE-2018-1058

see: https://www.postgresql.org/about/news/1834/ for more information bugfixes.
Signed-off-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/postgresql/postgresql.hash

@@ -1,4 +1,4 @@
-# From https://ftp.postgresql.org/pub/source/v9.6.7/postgresql-9.6.7.tar.bz2.sha256
-sha256 2ebe3df3c1d1eab78023bdc3ffa55a154aa84300416b075ef996598d78a624c6  postgresql-9.6.7.tar.bz2
+# From https://ftp.postgresql.org/pub/source/v9.6.8/postgresql-9.6.8.tar.bz2.sha256
+sha256 eafdb3b912e9ec34bdd28b651d00226a6253ba65036cb9a41cad2d9e82e3eb70  postgresql-9.6.8.tar.bz2
 # License file, Locally calculated
 sha256 24cfc70cf16b3a23242c49ffce39510683bdd48cbedb8a46fe03976ee5f5c21e  COPYRIGHT

package/postgresql/postgresql.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-POSTGRESQL_VERSION = 9.6.7
+POSTGRESQL_VERSION = 9.6.8
 POSTGRESQL_SOURCE = postgresql-$(POSTGRESQL_VERSION).tar.bz2
 POSTGRESQL_SITE = http://ftp.postgresql.org/pub/source/v$(POSTGRESQL_VERSION)
 POSTGRESQL_LICENSE = PostgreSQL