[PATCH, RFC] Fix codecvt_members_unicode_char.cc on s390/powerpc

[Paolo Carlini]

Paolo Carlini wrote:

> Hi,
>
> I have prepared the below, directly inspired by Ulrich analysis, which I find compelling.

A few punctualizations which I forgot to add to my previous message. To summarize, I believe
that:
1- Ulrich analysis is correct.
2- Alpha, at least on Linux, is little-endian, and that's why currently the test passes on
it.
3- Sparc is big-endian, but _GLIBCPP_USE___ENC_TRAITS is /undefined/ on the systems where
the tests /appear/ to pass. Therefore, the test is not really carried out.

Ciao,
Paolo.