When initiating a pivot or abort of a block job we need to track which
one was initiated. Currently it was done via data stashed in
virDomainDiskDef. Add possibility to track this also together with the
job itself.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>