bug#19909: [PATCH] Error out if with-file-notification=w32 is specified on cygwin

[Eli Zaretskii]

> Date: Fri, 27 Feb 2015 17:25:54 -0500
> From: Ken Brown <kbrown@cornell.edu>
> CC: bug-gnu-emacs@gnu.org, rpluim@gmail.com
> 
> It looks like it might not take much effort.  What I did for now, just 
> for testing purposes, is to copy into w32notify.c whatever was necessary 
> to make the Cygwin-w32 build compile with w32 file notification.  I 
> tested it briefly and it seems to work.  Obviously it needs much more 
> testing to make sure this doesn't break anything else, and then we can 
> worry about how to do this right.

Thanks.  A few comments:

  . Cygwin doesn't need to call MultiByteToWideChar and
    WideCharToMultiByte via function pointers, it can call them
    directly.

  . I think there shouldn't be a need to call filename_to_utf16 and
    its ilk, but instead use the to_unicode etc., like the rest of
    Cygwin-w32 code does.  E.g., just use GUI_ENCODE_FILE defined on
    w32term.h.