Revision 1378704

- fixes from v241-stable branch
  * sd-device: also store properties read from udev database to 
    sd_device::properties_db
  * udev-event: make subst_format_var() always provide null-terminated
    string on success
  * login: HyperV requires master-of-seat to be set
  * login: mark nomodeset fb devices as master-of-seat