Recently CPU hardware vendors have started to support a new structure
inside the CPU package topology known as a "die". Thus the hierarchy
is now:

  sockets > dies > cores > threads

This adds support for "dies" in the XML parser, with the value
defaulting to 1 if not specified for backwards compatibility.

For example a system with 64 logical CPUs might report

   <topology sockets="4" dies="2" cores="4" threads="2"/>
Reviewed-by: NJiri Denemark <jdenemar@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

While "x86" is a CPU sub driver name, it is not a recognized name of any
architecture known to libvirt. Let's use "x86_64" prefix which can be
used with virArch APIs.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

QEMU 2.3 adds these new models to cover Haswell and Broadwell CPUs with
updated microcode. Luckily, they also reverted former the machine type
specific changes to existing models. And since these changes were never
released, we don't need to hack around them in libvirt.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>