Fix-for-ticket-47972 - make parsing of nsslapd-changelogmaxage more fault tolerant
    
    When configuring nsslapd-changelogmaxage as a single non numeric character (e.g. "-")
    you end up with a changelog that is completely purged with the next run of the purge
    thread.  The problem is only logged for log level PLUGIN,
    
    As a fix:
    in age_str2time: return 0 if unit cannot be parsed and log the error message as FATAL,
    so you will at least have a default changelogmaxage and may notice the error message.
    
    https://fedorahosted.org/389/ticket/47972
    
    Resolves: Ticket 47972
    Bug Description: make parsing of nsslapd-changelogmaxage more fault tolerant
    Reviewed by: mreynolds@redhat.com, nhosoi@redhat.com
    Branch: master
    Fix Description: return 0 for unparseable values and log as FATAL
    Platforms tested: Centos 6.6
    Flag Day: no
    Doc impact: no