[RFA-v2] Handle cygwin wchar_t specifics

[Eli Zaretskii]

> From: "Pierre Muller" <pierre.muller@ics-cnrs.unistra.fr>
> Cc: "'Tom Tromey'" <tromey@redhat.com>, <gdb-patches@sourceware.org>
> Date: Sat, 16 Apr 2011 23:28:35 +0200
> 
> -/* If __STDC_ISO_10646__ is defined, then the host wchar_t is UCS-4.
> +/* If __STDC_ISO_10646__ is defined, then the host wchar_t is UCS-4 or UCS-2.

Please use UTF-16, not UCS-2.  What Windows uses is the former.  The
latter is the old name from the days when Unicode covered only the
BMP; it was superseded by UTF-16 that covers more than that.