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>

SVN-Revision: 47360