do not forbid the empty pattern

[Ralf Wildenhues]

While looking at glibc's usage of m4_wrap, I got sidetracked on this
issue ... OK to apply this "interesting" bug fix, which should make
CVS glibc buildable with CVS Autoconf?

(I added the ^$ to the search line rather than the list of allowed
tokens so it does not clutter the --verbose output.)

Cheers,
Ralf

        * bin/autom4te.in (handle_output): Do not forbid the empty
        pattern.
        * tests/tools.at (autoconf: the empty token): New test.

Index: bin/autom4te.in
===================================================================
RCS file: /cvsroot/autoconf/autoconf/bin/autom4te.in,v
retrieving revision 1.98
diff -u -r1.98 autom4te.in
--- bin/autom4te.in     4 Jun 2006 19:56:27 -0000       1.98
+++ bin/autom4te.in     19 Jun 2006 18:32:34 -0000
@@ -572,7 +572,7 @@
       foreach (split (/\W+/))
        {
          $prohibited{$_} = $.
-           if /$forbidden/o && !/$allowed/o && ! exists $prohibited{$_};
+           if !/^$/ && /$forbidden/o && !/$allowed/o && ! exists 
$prohibited{$_};
        }
 
       # Performed *last*: the empty quadrigraph.
Index: tests/tools.at
===================================================================
RCS file: /cvsroot/autoconf/autoconf/tests/tools.at,v
retrieving revision 1.88
diff -u -r1.88 tools.at
--- tests/tools.at      6 Jun 2006 14:51:01 -0000       1.88
+++ tests/tools.at      19 Jun 2006 18:32:15 -0000
@@ -322,8 +322,23 @@
 AT_CLEANUP
 
 
+# autoconf: do not forbid the empty token
+# ---------------------------------------
+AT_SETUP([autoconf: the empty token])
+
+AT_DATA_M4SH([configure.ac],
+[[m4_pattern_allow([^foo$])
+m4_divert([0])dnl
+ line that begins with a space
+]])
+
+AT_CHECK_AUTOCONF
+
+AT_CLEANUP
+
+
 # autoconf: subdirectories
-# --------------------------------------
+# ------------------------
 AT_SETUP([autoconf: subdirectories])
 
 AT_DATA([configure.ac],