qemu: make advice from numad available when building commandline

qemu: make advice from numad available when building commandline

Particularly in qemuBuildNumaArgStr(), there was a need for the advice
due to memory backing, which needs to know the nodeset it will be pinned
to.  With newer qemu this caused the following error when starting
domain:

  error: internal error: Advice from numad is needed in case of
  automatic numa placement

even when starting perfectly valid domain, e.g.:

  ...
  <vcpu placement='auto'>4</vcpu>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>
  <cpu>
    <numa>
      <cell id='0' cpus='0' memory='524288'/>
      <cell id='1' cpus='1' memory='524288'/>
    </numa>
  </cpu>
  ...

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1138545

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>