clufter.spec: factor "borrow schemas from pacemaker" out to a script
    
    It wasn't economical to carry all the current-at-pacemaker-release CIB
    validation schemas, as there are clear update/versioning rules[1]:
    - non-conflicting addtions: keep the same major version
    - conflicting changes: bump the major version, craft the update path
      (as XSLT)
    and hence everything in X.Y is subsumed with X.Y+1 incl. some proper
    additions.  Therefore we carry just the latest minor version for each
    major one, and because of locally established (not necessarily true
    for pacemaker) update-just-to-lowest-minor-per-new-major rule
    (usually X.Y -> X+1.0), we add also these lowest minor counterparts,
    to validate the sanity of the upgrade if not for anything else.
    As an exception, we avoid pacemaker-1.0 schema as the lowest common
    denominator we have in mind is pacemaker-1.2 and we don't support
    upgrade from pre-1.0 schema version, anyway.
    
    [1] https://github.com/ClusterLabs/pacemaker/tree/Pacemaker-1.1.17-rc3/xml#updating-schema-files
    
    Signed-off-by: Jan Pokorný <jpokorny@redhat.com>