tests/qapi-schema: Document alternate's enum lacks visit function We generate a declaration, but no definition. The QMP schema has two: Qcow2OverlapChecks and BlockdevRef. Neither visit_type_Qcow2OverlapChecksKind() nor visit_type_BlockdevRefKind() is actually used. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>