fedora-common-ostree: Workaround for SAMBA support in cups
    
    RPM %triggerin are not currently supported in rpm-ostree, thus work
    around this issue by manually creating the symlink.
    
    According to the docs, `/usr/lib/cups/backend/smb` should point to `smbspool`.
    Here we have the following chain:
    
    /usr/lib/cups/backend/smb -> /usr/libexec/samba/cups_backend_smb -> /etc/alternatives/cups_backend_smb -> /usr/bin/smbspool
    
    See: https://www.cups.org/blog/2005-06-17-printing-to-windows-servers-with-samba.html
    See: https://github.com/coreos/rpm-ostree/issues/1180
    See: https://github.com/fedora-silverblue/issue-tracker/issues/532
    See: https://pagure.io/workstation-ostree-config/pull-request/456