Ticket #47835 - Coverity: 12687..12692
    
    12687 - Unbounded source buffer
    Description: To solve "Passing string argv[0] of unknown size to
    usage, which expects a string of a particular size", get ARG_MAX
    and pass it to slapi_ch_strndup.
    
    Reviewed by rmeggins@redhat.com (Thanks, Rich!)
    
    https://fedorahosted.org/389/ticket/47835