XenAPI: Allow use of clone_vdi on all SR types

All XenServer SR types support VDI.clone - even if they perform
an internal VDI.copy.  Always use the clone function if COW is
enabled.

Change-Id: I85c580fba43d3bb52149626419d0f0c03ed69145
libvirt: VM diagnostics (v3 API only)

There is no formal definition for the VM diagnostics. For the
V2 API the diagnostics will be returned as they are today.

For the V3 api the diagnostics will have the format defined at:
https://wiki.openstack.org/wiki/Nova_VM_Diagnostics

This will support backward compatibility with the existing API's.

Part of the blueprint v3-diagnostics

DocImpact

Change-Id: Id722f38fb134b322413d2b5c3459c8fc0af7bd36
XenAPI: Use direct IO for writing config drive

If you don't use direct IO when writing to the device, the unplug
immediately following this may not succeed as the device may still
be in use.

Also add a sync to ensure the device is not being used at the point
of unplug.

Closes-bug: 1259163

Change-Id: I68f09835648b36772a7839af9718123a4c60734f
XenAPI: VM diagnostics for v3 API

For V3 API the diagnostics will have the format defined at:
https://wiki.openstack.org/wiki/Nova_VM_Diagnostics

This will support backward compatability with the existing APIs

Part of the blueprint v3-diagnostics

DocImpact

Change-Id: I8377f86a97ca554028e4ca8c1c1af7fd5643cc2e
XenAPI: get_info was very expensive

Getting the whole VM record is expensive and slowed down Tempest tests
significantly.  Replaced with getting each required item.

When getting power state, only need that specific value, so reduce the
calls to get_info too.

Change-Id: I93bcef5b692a531aac41518dc29d5d4f46cded65
XenAPI: Tidy calls to get_all_ref_and_rec

get_all_records is more efficient than getting them individually in the
old get_all_ref_and_rec implementation.

Replaced some cases of get_all_records with a faster and more
specific API call.

Change-Id: I4725c3f1fdebdf1737941cb7db69b19afb22df9f
XenAPI: Speedup get_vhd_parent_uuid

In many cases the VDI record has already been retrieved.
Use it rather than expensively getting a new VDI record from XAPI.

Change-Id: I469e2a415c1f1924010f47d3927ca18c45a7b8f8
XenAPI: Use get_VALUE in preference to get_record()['VALUE']

Replaces calls to get_record where only a single item is retrieved
from the record with the specific get_VALUE call.

Change-Id: I52e20c4f4c9d6a6ad019694916ee057cc96b18a6
XenAPI: Monitor the GC when coalescing

Add a new host plugin to monitor whether the garbage collector is running.
This is then used by the wait_for_vhd_coalesce function to know whether
waiting any more is likely to produce the expected results.

Increased the number of times we loop waiting for coalesce as the loop
now has knowledge that something is still happening.

Change-Id: Idcc0738945bd1aee8cdb52c9cfabd798f85c31db
Closes-bug: 1258169
XenAPI: get_info was very expensive

Getting the whole VM record is expensive and slowed down Tempest tests
significantly.  Replaced with getting each required item.

When getting power state, only need that specific value, so reduce the
calls to get_info too.

Change-Id: I93bcef5b692a531aac41518dc29d5d4f46cded65
XenAPI: Tidy calls to get_all_ref_and_rec

get_all_records is more efficient than getting them individually in the
old get_all_ref_and_rec implementation.

Replaced some cases of get_all_records with a faster and more
specific API call.

Change-Id: I4725c3f1fdebdf1737941cb7db69b19afb22df9f
XenAPI: Report the CPU details correctly

Driver was not filling in the cpu_count in the correct field.
Also added VM vcpu count

Change-Id: I6339d7fd4faffcd5320fd86b55ff3a5e3515e2bf
Closes-bug: 1192528
Merge commit 'refs/changes/53/58753/9' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch
Merge commit 'refs/changes/54/58754/11' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch
Merge commit 'refs/changes/55/58755/10' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch
Merge commit 'refs/changes/61/58861/10' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch
Merge commit 'refs/changes/53/60253/7' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch

Conflicts:
	nova/virt/xenapi/vm_utils.py
Merge commit 'refs/changes/08/60808/6' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch
Merge commit 'refs/changes/78/63778/1' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch
Merge commit 'refs/changes/38/66338/3' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch