init: if libc-based Unicode support is on, run setlocale(LC_ALL, "") at startup

It is not clear why we were excluding init from this.
The "getpid() != 1" clause was there from the beginning (2001)
but not explained.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
hush: make ${#var} unicode-aware

This mimics bash

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
ash,hush: run reinit_unicode() only if makes sense

With static Unicode support, no need to check $LANG et al.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
ash: make ${#var} unicode-aware

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
addgroup: mention -S in the help text

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>