* grp.cc: Call gr.refresh() rather than doing isunitialized tests throughout.

* grp.cc: Call gr.refresh() rather than doing isunitialized tests throughout.
(gr): Use constructor (sigh).
(pwdgrp::parse_group): Rename from parse_grp.
(pwdgrp::read_group): Rename from read_etc_group.  Just call gr.load with a
single argument.
* passwd.cc: Call pr.refresh() rather than doing isunitialized tests
throughout.
(pr): Use constructor (sigh).
(pwdgrp::parse_passwd): Rename from "parse_pwd".
(pwdgrp::read_passwd): Rename from read_etc_passwd.  Just call pr.load with a
single argument.
* pwdgrp.h (pwdgrp_state): Eliminate.
(pwdgrp): Reflect above renamings.
(pwdgrp::etc_ix): Rename from pwd_ix.
(pwdgrp::read): New element.
(pwdgrp::lock): New element.
(pwdgrp::refresh): New function.
(pwdgrp::load): Eliminate variations which take buffer arguments.
(pwdgrp::pwdgrp): New constructors.  Initialize mutex here.
* uinfo.cc (pwdgrp::load): Accommodate pwd_ix -> etc_ix renaming.
(pwdgrp::load): Set initialized state to true rather than setting state to
loaded.