initial attempt at supporting non-host-arch builds
initial attempt at supporting non-host-arch builds

This uses the capabilities XML in libvirt to detect and use non-host
and non-accelerated virtualization if it is available.  This allows,
for example, attempting to build 32 bit ARM on x86_64 hosts.

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