Update the host CPU code to report the die_id in the NUMA topology
capabilities. On systems with multiple dies, this fixes the bug
where CPU cores can't be distinguished:

 <cpus num='12'>
   <cpu id='0' socket_id='0' core_id='0' siblings='0'/>
   <cpu id='1' socket_id='0' core_id='1' siblings='1'/>
   <cpu id='2' socket_id='0' core_id='0' siblings='2'/>
   <cpu id='3' socket_id='0' core_id='1' siblings='3'/>
 </cpus>

Notice how core_id is repeated within the scope of the same socket_id.

It now reports

 <cpus num='12'>
   <cpu id='0' socket_id='0' die_id='0' core_id='0' siblings='0'/>
   <cpu id='1' socket_id='0' die_id='0' core_id='1' siblings='1'/>
   <cpu id='2' socket_id='0' die_id='1' core_id='0' siblings='2'/>
   <cpu id='3' socket_id='0' die_id='1' core_id='1' siblings='3'/>
 </cpus>

So core_id is now unique within a (socket_id, die_id) pair.
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: NJiri Denemark <jdenemar@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>