Fix PR 8120

[Neil Booth]

This is a documentation update, applied to 3.2.  It doesn't affect
3.3.

Neil.

	PR preprocessor/8120
	* doc/cpp.texi: Update documentation of bad use of ##.

Index: doc/cpp.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/cpp.texi,v
retrieving revision 1.24.2.3.4.2
diff -u -p -r1.24.2.3.4.2 cpp.texi
--- doc/cpp.texi	30 Sep 2002 17:35:44 -0000	1.24.2.3.4.2
+++ doc/cpp.texi	5 Oct 2002 09:34:24 -0000
@@ -3736,9 +3736,9 @@ Here are a few more obsolete features.
 @item Attempting to paste two tokens which together do not form a valid
 preprocessing token.
 
-The preprocessor currently warns about this and outputs the two tokens
-adjacently, which is probably the behavior the programmer intends.  It
-may not work in future, though.
+The preprocessor currently warns about this, and the resulting
+preprocessed output is undefined.  The tokens remain distinct if the
+preprocessor is being used directly by the compiler front end.
 
 Most of the time, when you get this warning, you will find that @samp{##}
 is being used superstitiously, to guard against whitespace appearing