libxl: avoid considering pCPUs outside of the cpupool during NUMA placement

libxl: avoid considering pCPUs outside of the cpupool during NUMA placement

During NUMA automatic placement, the information
of how many vCPUs can run on what NUMA nodes is used,
in order to spread the load as evenly as possible.

Such information is derived from vCPU hard and soft
affinity, but that is not enough. In fact, affinity
can be set to be a superset of the pCPUs that belongs
to the cpupool in which a domain is but, of course,
the domain will never run on pCPUs outside of its
cpupool.

Take this into account in the placement algorithm.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Reported-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>