Libvirt Windows Timer tests fail on a Mac

[Rick Harris]

We have some tests that assert that the KVM timers are appropriately set for Windows.

The issue is that the test depends on the actual result of `processor.platform()` which will be `i386` on a Mac.

We need to stub the `get_arch` function out so that it always returns `arch.i686` so the test behaves consistently across platforms.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/145618

[Johannes Erdfelt (johannes.erdfelt)]

I had a similar problem with platform.processor() but on Linux:

>>> import platform
>>> platform.processor()
''

My system reports an empty string for platform.processor() :(

The docs for platform.processor() states "An empty string is returned if the value cannot be determined."

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/145618
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=10acedd704f9cb5bc5ca62769c98c23fa1cbdb6f
Submitter: Jenkins
Branch: master

commit 10acedd704f9cb5bc5ca62769c98c23fa1cbdb6f
Author: Rick Harris <email address hidden>
Date: Wed Jan 7 16:52:34 2015 -0600

    libvirt: Use arch.from_host instead of platform.processor

    The Windows timer tests would fail on a Mac because it would return `i386`
    from `get_arch` instead of one of the canonicalized architecture names.

    The solution is to use the standardized `arch.from_host` function instead.

    We still mock out the `get_arch` function so the tests pass on PPC/ARM/s390
    processors.

    Co-Authored-By: Daniel Berrange <email address hidden>
    Change-Id: Id3cd1311c91c21a50f43ea46cc8451b349fb5862
    Closes-Bug: 1408484