postgresql: update to version 9.6.8

This update addresses:

CVE-2018-1052
CVE-2018-1053
CVE-2018-1058

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

libs/postgresql/Makefile

@@ -5,7 +5,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=postgresql
-PKG_VERSION:=9.6.6
+PKG_VERSION:=9.6.8
 PKG_RELEASE:=1
 PKG_MAINTAINER:=Daniel Golle <daniel@makrotopia.org>
 PKG_LICENSE:=PostgreSQL
@@ -16,7 +16,7 @@ PKG_SOURCE_URL:=\
 	http://ftp.postgresql.org/pub/source/v$(PKG_VERSION) \
 	ftp://ftp.postgresql.org/pub/source/v$(PKG_VERSION)
 
-PKG_HASH:=399cdffcb872f785ba67e25d275463d74521566318cfef8fe219050d063c8154
+PKG_HASH:=eafdb3b912e9ec34bdd28b651d00226a6253ba65036cb9a41cad2d9e82e3eb70
 
 PKG_USE_MIPS16:=0
 PKG_FIXUP:=autoreconf