We historically format runtime seclabel selinux/apparmor values,
however we skip formatting runtime DAC values. This was added in

commit 990e46c4
Author: Marcelo Cerri <mhcerri@linux.vnet.ibm.com>
Date:   Fri Aug 31 13:40:41 2012 +0200

    conf: Avoid formatting auto-generated DAC labels

to maintain migration compatibility with libvirt < 0.10.0.

However the formatting was skipped unconditionally. Instead only
skip formatting in the VIR_DOMAIN_DEF_FORMAT_MIGRATABLE case.

https://bugzilla.redhat.com/show_bug.cgi?id=1215833