virt-aa-helper: Call virCommandRawStatus()

virt-aa-helper: Call virCommandRawStatus()

The way we're processing the return status, using WIFEXITED() and
friends, only works when we have the raw return status; however,
virCommand defaults to processing the return status for us. Call
virCommandRawStatus() before virCommandRun() so that we get the raw
return status and the logic can actually work.

This results in guest startup failures caused by AppArmor issues
being reported much earlier: for example, if virt-aa-helper exits
with an error we're now reporting

  error: internal error: cannot load AppArmor profile 'libvirt-b20e9a8e-091a-45e0-8823-537119e98bc6'

instead of the misleading

  error: internal error: Process exited prior to exec: libvirt:
  error : unable to set AppArmor profile 'libvirt-b20e9a8e-091a-45e0-8823-537119e98bc6'
  for '/usr/bin/qemu-system-x86_64': No such file or directory

Suggested-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>