security: DAC: fix the transaction model's list append

security: DAC: fix the transaction model's list append

The problem is in the way how the list item is created prior to
appending it to the transaction list - the @path attribute is just a
shallow copy instead of deep copy of the hostdev device's path.
Unfortunately, the hostdev devices from which the @path is extracted, in
order to add them into the transaction list, are only temporary and
freed before the buildup of the qemu namespace, thus making the @path
attribute in the transaction list NULL, causing 'permission denied' or
'double free' or 'unknown cause' errors.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1413773

Signed-off-by: Erik Skultety <eskultet@redhat.com>