journald: correctly attribute log messages also with cgroupsv1
    
    With cgroupsv1 a zombie process is migrated to root cgroup in all
    hierarchies. This was changed for unified hierarchy and /proc/PID/cgroup
    reports cgroup to which process belonged before it exited.
    
    Be more suspicious about cgroup path reported by the kernel and use
    unit_id provided by the log client if the kernel reports that process is
    running in the root cgroup.
    
    Users tend to care the most about 'log->unit_id' mapping so systemctl
    status can correctly report last log lines. Also we wouldn't be able to
    infer anything useful from "/" path anyway.
    
    See: https://github.com/torvalds/linux/commit/2e91fa7f6d451e3ea9fec999065d2fd199691f9d
    
    (cherry picked from commit 672773b63a4ebf95242b27e63071b93073ebc1f5)
    
    Resolves: #1658115
    
    patch_name: 0086-journald-correctly-attribute-log-messages-also-with-.patch
    present_in_specfile: true
    location_in_specfile: 86
    squash_commits: true