* src/options.c(option_b): take a service name, and a default enable
    	and disable list.  If we have no command-line argument, check for the
    	service's name in the list of values given in the config file, then
    	check for a regular boolean setting in the configuration file, and
    	lastly check our default configuration using the default enable and
    	disable lists.
    * src/pam_krb5.5.in,src/pam_krb5.8.in: note that boolean options take
    	lists of service names now.