update config.guess & config.sub

update config.guess & config.sub

These are from today's master branch of:
http://git.savannah.gnu.org/gitweb/?p=config.git;a=tree

In particular it adds support for ARC architecture plus some more
improvements and fixes.

This patch is built-tested against NetGear WNDR3800.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Imre Kaloz <kaloz@openwrt.org>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@47360 3c298f89-4303-0410-b956-a3cf2f4a3e73