bug#14901: Trunk bootstrap broken

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Fri, 19 Jul 2013 01:17:13 +0200
> Cc: 14901@debbugs.gnu.org
> 
> > After Paul's changes, rev. 113451 bootstraps... Thanks.
> 
> Yes, I just saw. Wonderful.

Not so wonderful.  (Doesn't anyone watch compiler warnings these
days?)  Using this:

    struct x_display_info *di;

on anything but X11 is a no-no, since that struct is not portable.
The portable way is to use Display_Info, which a type defined on any
platform we support (including TTYs and even MS-DOS).  No need for the
DISPLAY_INFO macro, either.

> But in ay case, could you please test that it works by changing WINDOWSNT
> to HAVE_NTGUI in that #ifdef? I think it's the right test anyway.

This whole rigmarole with multiple HAVE_* is not needed at all, since
HAVE_WINDOW_SYSTEM captures all of them.

I fixed both of the above in trunk revision 113456.  I've verified
this to compile on GNU/Linux and on MS-Windows, I expect the NS port
will build without any problems, too.