[PATCH] fix wide character literal use in some test cases

[Paolo Carlini]

Paolo Carlini wrote:

>...                                           and in the C++ library we
>don't really support targets encoding plain chars with more than 8 bits.
>
By the way, if I'm not mistaken, among the targets supported by the
compiler proper, there are just very few using 32 bits for char and for
those, really, a 32-bit proper constant is not ""more random"" than a
16-bit one.

Paolo.