qemuxml2xmltest: Set dummy non-hypervisor drivers
qemuxml2xmltest: Set dummy non-hypervisor drivers

When parsing domain XML post parse callbacks are run and one of
them might try and call API from a non-hypervisor driver (e.g.
just like qemuDomainDeviceNetDefPostParse() is doing - it calls a
network API). To avoid this in the test suite, set dummy drivers,
which renders all non-hypervisor APIs return error.

This mimics what qemuxml2argvtest does.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>
Reviewed-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

crobinso/libvirt,crobinso/libvirt,olafhering/libvirt,nertpinx/libvirt,libvirt/libvirt,libvirt/libvirt,jardasgit/libvirt,crobinso/libvirt,zippy2/libvirt,jfehlig/libvirt,zippy2/libvirt,nertpinx/libvirt,nertpinx/libvirt,nertpinx/libvirt,jardasgit/libvirt,zippy2/libvirt,jardasgit/libvirt,olafhering/libvirt,jardasgit/libvirt,jardasgit/libvirt,jfehlig/libvirt,libvirt/libvirt,jfehlig/libvirt,olafhering/libvirt,zippy2/libvirt,libvirt/libvirt,olafhering/libvirt,jfehlig/libvirt,crobinso/libvirt,nertpinx/libvirt