[patch] fix "broken pipe" message from lseek test

[Ben Pfaff]

Hi Eric.

I noticed that (sometimes?) the lseek check prints a "broken
pipe" message in the middle of "configure" output, e.g.
        checking whether lseek detects pipes... ../configure: line 30326: echo: 
write error: Broken pipe
as reported here under step 19:
        http://benpfaff.org/~blp/pspp-master/20100220040512/

I think that we should redirect stderr to /dev/null for that
test.

May I push the following to gnulib?

Thanks,

Ben.

commit 917e141b6d1a764e3af86684047202c14b7dadde
Author: Ben Pfaff <address@hidden>
Date:   Sat Feb 20 10:58:45 2010 -0800

    Avoid "broken pipe" message from lseek test.
    
    * m4/lseek.m4: Redirect stderr to /dev/null when writing to a pipe
      that will not be read from.

diff --git a/ChangeLog b/ChangeLog
index 9d3367e..01e1f41 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-02-20  Ben Pfaff  <address@hidden>
+
+       Avoid "broken pipe" message from lseek test.
+       * m4/lseek.m4: Redirect stderr to /dev/null when writing to a pipe
+       that will not be read from.
+
 2010-02-19  Bruno Haible  <address@hidden>
 
        Make it easier to find modules. New gnulib-tool option '--find'.
diff --git a/m4/lseek.m4 b/m4/lseek.m4
index f308495..bbf449d 100644
--- a/m4/lseek.m4
+++ b/m4/lseek.m4
@@ -1,4 +1,4 @@
-# lseek.m4 serial 4
+# lseek.m4 serial 5
 dnl Copyright (C) 2007, 2009, 2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -21,7 +21,7 @@ int main ()
 }],
          [if test -s conftest$ac_exeext \
              && ./conftest$ac_exeext < conftest.$ac_ext \
-             && { echo hi | ./conftest$ac_exeext; test $? = 1; }; then
+             && { echo hi 2>/dev/null | ./conftest$ac_exeext; test $? = 1; }; 
then
             gl_cv_func_lseek_pipe=yes
           else
             gl_cv_func_lseek_pipe=no

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"It's like herding cats, only most of the engineers are already
 sick of laser pointers."