libvpx: bump to 1.6.0

This release improves upon the VP9 encoder and speeds up the encoding
and decoding processes.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>

libs/libvpx/Makefile

@@ -1,5 +1,6 @@
 #
 # Copyright (C) 2008-2015 OpenWrt.org
+# Copyright (C) 2016 Luiz Angelo Daros de Luca
 #
 # This is free software, licensed under the GNU General Public License v2.
 # See /LICENSE for more information.
@@ -8,7 +9,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=libvpx
-PKG_VERSION:=1.5.0
+PKG_VERSION:=1.6.0
 PKG_RELEASE:=1
 
 PKG_REV:=v$(PKG_VERSION)