[CentOS-virt] CentOS 6 Xen package update (including XSA-156)

[George Dunlap]

So going forward, we're moving the CentOS 6 Xen packages from the
custom "xen4" repos that were introduced several years ago, to repos
based on its position as a sub-project of the Virt Sig.  That will
make things consistent between all the sigs, as well as between CentOS
6 and 7 Xen packages.

Unfortunately, XSA-156 came up rather suddenly and is a bit blocked by
this transition.

So please help us test the new repository structure, so that we can
with conscience push the updates to xen4 users in general.

To update to the new repository structure, install the
centos-release-xen package directly from the new repo:

 yum update http://mirror.centos.org/centos/6/virt/x86_64/xen/centos-release-xen-7-11.el6.x86_64.rpm

This should replace the xen4 repositories with the new virt sig
repositories.  Now do a 'yum update':

yum update

This should pull in the Xen 4.4.3-6 package, which contains XSA-156
(and all other packages).

If everything works as planned, we'll push the new centos-release-xen
to centos-extras, and then everyone else will be moved to the new
repos the next time they do an update.

 -George