Bug 529258 - Make upgrade remove obsolete schema from 99user.ldif
    
    Due to a previously fixed bug (bz 474254), standard schema may
    have been duplicated in 99user.ldif.  When running an upgrade, we
    need to check the 99user.ldif file to see if any obsolete standard
    schema is defined there and remove it.
    
    This patch makes upgrade backup the original 99user.ldif, and
    scans it to see if any of the obsolete attributeTypes or
    objectClasses attributes that we are removing from the standard
    schema exist in 99user.ldif.  We trim the obsolete definitions
    and write out a new 99user.ldif with the proper permissions.