bug#15880: Compute C declarations for DEFSYMs automatically.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 07 Jan 2015 17:16:41 -0800
> From: Paul Eggert <eggert@cs.ucla.edu>
> 
> Glenn Morris wrote:
> >
> > This change causes `make check' to fail; specifically in file-notify-tests.
> 
> Thanks for reporting that bug.  I reproduced the problem and installed the 
> attached patch, which fixes it for me.
> 
> >From d71659fed4eb87eb3edbf8f83fb0e9ed2633fa74 Mon Sep 17 00:00:00 2001
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Wed, 7 Jan 2015 17:12:16 -0800
> Subject: [PATCH] Port GFileMonitor * hack to Qnil==0 platforms
> 
> Reported by Glenn Morris in: http://bugs.gnu.org/15880#112
> * gfilenotify.c (monitor_to_lisp, lisp_to_monitor): New functions.
> (dir_monitor_callback, Fgfile_add_watch, Fgfile_rm_watch): Use them.
> ---
>  src/ChangeLog     |  7 +++++++
>  src/gfilenotify.c | 33 +++++++++++++++++++++++----------
>  2 files changed, 30 insertions(+), 10 deletions(-)
> 
> diff --git a/src/ChangeLog b/src/ChangeLog
> index 8680c5e..2fc3479 100644
> --- a/src/ChangeLog
> +++ b/src/ChangeLog
> @@ -1,3 +1,10 @@
> +2015-01-08  Paul Eggert  <eggert@cs.ucla.edu>
> +
> +	Port GFileMonitor * hack to Qnil==0 platforms
> +	Reported by Glenn Morris in: http://bugs.gnu.org/15880#112
> +	* gfilenotify.c (monitor_to_lisp, lisp_to_monitor): New functions.
> +	(dir_monitor_callback, Fgfile_add_watch, Fgfile_rm_watch): Use them.

Could we instead just keep the previous semantics of XIL and XLI,
please?  They are used in a few places outside lisp.h, so now all of
those places need to be audited and most probably changed.  Why isn't
it better to change the implementation of just 2 macros instead?