Fix building i386/i386 on x86_64 hosts.
Fix building i386/i386 on x86_64 hosts.

The change to allow non-host builds actually broke
building i386 on x86_64.  This is because libvirt
refers to the architecture as i686, while Oz refers
to it as i386.  Add in a mapping for libvirt so we
avoid the problem.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@gmail.com>

mgagne/oz,imcleod/oz,mgagne/oz,ndonegan/oz,nullr0ute/oz,moofrank/oz,imcleod/oz,ndonegan/oz,clalancette/oz,clalancette/oz,moofrank/oz,nullr0ute/oz