Merge "objects: Move 'arch' to 'fields.Architecture'"

diff --cc nova/tests/unit/virt/libvirt/test_blockinfo.py
Simple merge

diff --cc nova/tests/unit/virt/libvirt/test_driver.py
Simple merge

diff --cc nova/virt/libvirt/blockinfo.py
Simple merge

diff --cc nova/virt/libvirt/driver.py
Simple merge