util: Continue if setlocale fails
    
    setlocale needs some environment variables
    to be set in order to work. These variables
    are not present in some special cases. We
    should not fail completely in these cases
    but continue with the compatible C locale.
    
    Resolves:
    https://fedorahosted.org/sssd/ticket/2785
    
    Reviewed-by: Michal Židek <mzidek@redhat.com>