sd-bus: introduce API for re-enqueuing incoming messages
    
    When authorizing via PolicyKit we want to process incoming method calls
    twice: once to process and figure out that we need PK authentication,
    and a second time after we aquired PK authentication to actually execute
    the operation. With this new call sd_bus_enqueue_for_read() we have a
    way to put an incoming message back into the read queue for this
    purpose.
    
    This might have other uses too, for example debugging.
    Related: CVE-2020-1712
    
    patch_name: 0314-sd-bus-introduce-API-for-re-enqueuing-incoming-messa.patch
    present_in_specfile: true
    location_in_specfile: 314
    squash_commits: true