security: SELinux: 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 argument 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>