Autoconf fails to recognise microblaze-xilinx-linux-gnu toolchain

Problem Description

On upgrading to Petalinux v12.12, you may receive an error similar to the  following while building an application or library you've ported from outside Petalinux which utilises autoconf:

checking host system type... Invalid configuration `microblaze-xilinx-linux-gnu': machine `microblaze-xilinx' not recognized
configure: error: /bin/sh ../libtestautoconf-0.1/config.sub microblaze-xilinx-linux-gnu failed

Background

An out of date config.sub in your application or library is unable to  recognise 'microblaze-xilinx' as a valid architecture-vendor pairing.

Workaround

Replace the outdated config.sub in your application or library with either the version included in 

$PETALINUX/etc/template/user-libs/template-autoconf/@libname@-0.1/config.sub

or the latest from upstream (http://savannah.gnu.org/projects/config) and rebuild.