The current schema is more permissive than the XML parsing code in
libvirt. Precisely, 'match' attribute is optional in schema while in
reality its use is bound to <model> element:
- <cpu> element without 'match' attribute is allowed only if <topology>
element is the only child element of <cpu>
- <cpu> element with 'match' attribute requires <model> element to be
present; <topology> and <feature> elements are optional
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>