libxl: Add lock process indicator to saved VM state

libxl: Add lock process indicator to saved VM state

Commit fa58f571ee added a lock processes indicator to the
libxlDomainObjPrivate struct to note that a lock process was
successfully started for the VM. However, the commit neglected to
add the indicator to the VM's saved state file. As a result, the
indicator is lost on libvirtd restart, along with the knowledge of
whether a lock process was started for the VM.

This change adds support for the indicator in the domainObjPrivate
data parse and format callbacks, ensuring its value survives libvirtd
restarts.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>