Document temporary directory `$tmp' for use in config.status.

[Ralf Wildenhues]

This came up in
<http://thread.gmane.org/gmane.comp.gcc.patches/192335/focus=192559>
and elsewhere.  What do you think about it?

Thanks,
Ralf

    Document temporary directory `$tmp' for use in config.status.
    
    * doc/autoconf.texi (Configuration Actions): Document `$tmp'.
    * NEWS: Update.

diff --git a/NEWS b/NEWS
index f2be8bf..8d7cba5 100644
--- a/NEWS
+++ b/NEWS
@@ -18,6 +18,9 @@ GNU Autoconf NEWS - User visible changes.
 
 ** config.status now provides a --config option to produce the configuration.
 
+** The `$tmp' temporary directory used in config.status is documented for
+   public use now.
+
 * Major changes in Autoconf 2.64 (2009-07-26) [stable]
   Released by Eric Blake, based on git versions 2.63b.*.
 
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 59b40c5..435e9ab 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -2191,6 +2191,14 @@ Configuration Actions
 @item ac_srcdir
 The name of the corresponding source directory, assuming that the
 working directory is the current build directory.
+
address@hidden tmp
+The name of a temporary directory within the build tree, which you
+can use if you need to create additional temporary files.  The
+directory is cleaned up when @command{config.status} is done or
+interrupted.  Please use package-specific file name prefixes to
+avoid clashing with files that @command{config.status} may use
+internally.
 @end table
 
 @noindent