Renamed from _nss_create_tablename. Export from file (but not DSO).
(pwd_tablename_val): Renamed from tablename_val, mark hidden.
(pwd_tablename_len): Renamed from tablename_len, mark hidden.
Change all users.
* nis/nss_nisplus/nisplus-spwd.c (_nss_create_tablename): Removed.
Use _nss_pwd_create_tablename now. Use pwd_tablename_val and
pwd_tablename_len. Remove unnecessary variables, general cleanup.
* nis/nss_nisplus/nisplus-grp.c: Likewise.