virCaps: expose pages info

virCaps: expose pages info

There are two places where you'll find info on page sizes. The first
one is under <cpu/> element, where all supported pages sizes are
listed. Then the second one is under each <cell/> element which refers
to concrete NUMA node. At this place, the size of page's pool is
reported. So the capabilities XML looks something like this:

<capabilities>

  <host>
    <uuid>01281cda-f352-cb11-a9db-e905fe22010c</uuid>
    <cpu>
      <arch>x86_64</arch>
      <model>Westmere</model>
      <vendor>Intel</vendor>
      <topology sockets='1' cores='1' threads='1'/>
      ...
      <pages unit='KiB' size='4'/>
      <pages unit='KiB' size='2048'/>
      <pages unit='KiB' size='1048576'/>
    </cpu>
    ...
    <topology>
      <cells num='4'>
        <cell id='0'>
          <memory unit='KiB'>4054408</memory>
          <pages unit='KiB' size='4'>1013602</pages>
          <pages unit='KiB' size='2048'>3</pages>
          <pages unit='KiB' size='1048576'>1</pages>
          <distances/>
          <cpus num='1'>
            <cpu id='0' socket_id='0' core_id='0' siblings='0'/>
          </cpus>
        </cell>
        <cell id='1'>
          <memory unit='KiB'>4071072</memory>
          <pages unit='KiB' size='4'>1017768</pages>
          <pages unit='KiB' size='2048'>3</pages>
          <pages unit='KiB' size='1048576'>1</pages>
          <distances/>
          <cpus num='1'>
            <cpu id='1' socket_id='0' core_id='0' siblings='1'/>
          </cpus>
        </cell>
        ...
      </cells>
    </topology>
    ...
  </host>

  <guest/>

</capabilities>

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>