* nscd/connections.c (dbs): Add initializers for .suggested_module.
(verify_persistent_db): Remove one unnecessary test and add a new one
for bad configuration.
(nscd_init): Improve error reported when persistent database cannot
be reused.
* nscd/nscd.h (DEFAULT_SUGGESTED_MODULE): Define.
* nscd/nscd_conf.c (nscd_parse_file): Provide default values for
.suggested_module and .max_db_size and case config file says the
values are zero.
* nscd/nscd_helper.c (get_mapping): Fail if hash table module is zero.