conf: fix populating of fake NUMA in multi-node hosts

conf: fix populating of fake NUMA in multi-node hosts

If the host OS doesn't have NUMA present, we fallback to
populating fake NUMA info and the code thus assumes only a
single NUMA node.

Unfortunately we also fallback to fake NUMA if numactl-devel
was not present, and in this case we can still have multiple
NUMA nodes. In this case we create all CPUs, but only the
CPUs in the first node have any data filled in, resulting in
capabilities like:

    <topology>
      <cells num='1'>
        <cell id='0'>
          <memory unit='KiB'>15977572</memory>
          <cpus num='48'>
            <cpu id='0' socket_id='0' core_id='0' siblings='0'/>
            <cpu id='1' socket_id='0' core_id='0' siblings='1'/>
            <cpu id='2' socket_id='0' core_id='1' siblings='2'/>
            <cpu id='3' socket_id='0' core_id='1' siblings='3'/>
            <cpu id='4' socket_id='0' core_id='2' siblings='4'/>
            <cpu id='5' socket_id='0' core_id='2' siblings='5'/>
            <cpu id='6' socket_id='0' core_id='3' siblings='6'/>
            <cpu id='7' socket_id='0' core_id='3' siblings='7'/>
            <cpu id='8' socket_id='0' core_id='4' siblings='8'/>
            <cpu id='9' socket_id='0' core_id='4' siblings='9'/>
            <cpu id='10' socket_id='0' core_id='5' siblings='10'/>
            <cpu id='11' socket_id='0' core_id='5' siblings='11'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
            <cpu id='0'/>
          </cpus>
        </cell>
      </cells>
    </topology>

With this new code we get something slightly less broken

    <topology>
      <cells num='4'>
        <cell id='0'>
          <memory unit='KiB'>15977572</memory>
          <cpus num='12'>
            <cpu id='0' socket_id='0' core_id='0' siblings='0-1'/>
            <cpu id='1' socket_id='0' core_id='0' siblings='0-1'/>
            <cpu id='2' socket_id='0' core_id='1' siblings='2-3'/>
            <cpu id='3' socket_id='0' core_id='1' siblings='2-3'/>
            <cpu id='4' socket_id='0' core_id='2' siblings='4-5'/>
            <cpu id='5' socket_id='0' core_id='2' siblings='4-5'/>
            <cpu id='6' socket_id='0' core_id='3' siblings='6-7'/>
            <cpu id='7' socket_id='0' core_id='3' siblings='6-7'/>
            <cpu id='8' socket_id='0' core_id='4' siblings='8-9'/>
            <cpu id='9' socket_id='0' core_id='4' siblings='8-9'/>
            <cpu id='10' socket_id='0' core_id='5' siblings='10-11'/>
            <cpu id='11' socket_id='0' core_id='5' siblings='10-11'/>
          </cpus>
        </cell>
        <cell id='0'>
          <memory unit='KiB'>15977572</memory>
          <cpus num='12'>
            <cpu id='12' socket_id='0' core_id='0' siblings='12-13'/>
            <cpu id='13' socket_id='0' core_id='0' siblings='12-13'/>
            <cpu id='14' socket_id='0' core_id='1' siblings='14-15'/>
            <cpu id='15' socket_id='0' core_id='1' siblings='14-15'/>
            <cpu id='16' socket_id='0' core_id='2' siblings='16-17'/>
            <cpu id='17' socket_id='0' core_id='2' siblings='16-17'/>
            <cpu id='18' socket_id='0' core_id='3' siblings='18-19'/>
            <cpu id='19' socket_id='0' core_id='3' siblings='18-19'/>
            <cpu id='20' socket_id='0' core_id='4' siblings='20-21'/>
            <cpu id='21' socket_id='0' core_id='4' siblings='20-21'/>
            <cpu id='22' socket_id='0' core_id='5' siblings='22-23'/>
            <cpu id='23' socket_id='0' core_id='5' siblings='22-23'/>
          </cpus>
        </cell>
      </cells>
    </topology>

The topology at least now reflects what 'virsh nodeinfo' reports.
The main bug is that the CPU "id" values won't match what the Linux
host actually uses.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>