Update from Gnulib

This incorporates:
2020-05-03 attribute: new module
2020-04-13 explicit_bzero: improve code style
2020-04-13 explicit_bzero: On native Windows, use SecureZeroMemory
2020-04-13 explicit_bzero: use memset_s() when available
2020-04-04 maint: remove a stray inter-word space
* build-aux/config.guess, build-aux/config.sub:
* build-aux/gitlog-to-changelog, build-aux/update-copyright:
* doc/misc/texinfo.tex, lib/explicit_bzero.c, lib/ieee754.in.h:
* lib/nstrftime.c, m4/explicit_bzero.m4, m4/gnulib-common.m4:
Copy from Gnulib.
* lib/attribute.h: New file, copied from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.

4 files changed, 14 insertions, 7 deletions

diff --git a/build-aux/config.guess b/build-aux/config.guess
index 45001cfecde..11fda528bc7 100755
--- a/build-aux/config.guess
+++ b/build-aux/config.guess
@@ -2,7 +2,7 @@
 # Attempt to guess a canonical system name.
 #   Copyright 1992-2020 Free Software Foundation, Inc.
 
-timestamp='2020-01-01'
+timestamp='2020-04-26'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -1629,6 +1629,12 @@ copies of config.guess and config.sub with the latest versions from:
   https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess
 and
   https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub
+EOF
+
+year=`echo $timestamp | sed 's,-.*,,'`
+# shellcheck disable=SC2003
+if test "`expr "\`date +%Y\`" - "$year"`" -lt 3 ; then
+   cat >&2 <<EOF
 
 If $0 has already been updated, send the following data and any
 information you think might be pertinent to config-patches@gnu.org to
@@ -1656,6 +1662,7 @@ UNAME_RELEASE = "$UNAME_RELEASE"
 UNAME_SYSTEM  = "$UNAME_SYSTEM"
 UNAME_VERSION = "$UNAME_VERSION"
 EOF
+fi
 
 exit 1
 
diff --git a/build-aux/config.sub b/build-aux/config.sub
index f02d43ad500..a0d12275ac5 100755
--- a/build-aux/config.sub
+++ b/build-aux/config.sub
@@ -2,7 +2,7 @@
 # Configuration validation subroutine script.
 #   Copyright 1992-2020 Free Software Foundation, Inc.
 
-timestamp='2020-01-01'
+timestamp='2020-04-24'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -1366,7 +1366,7 @@ case $os in
 	     | skyos* | haiku* | rdos* | toppers* | drops* | es* \
 	     | onefs* | tirtos* | phoenix* | fuchsia* | redox* | bme* \
 	     | midnightbsd* | amdhsa* | unleashed* | emscripten* | wasi* \
-	     | nsk* | powerunix)
+	     | nsk* | powerunix*)
 	# Remember, each alternative MUST END IN *, to match a version number.
 		;;
 	qnx*)
diff --git a/build-aux/gitlog-to-changelog b/build-aux/gitlog-to-changelog
index 511276757f5..be8082e7ffd 100755
--- a/build-aux/gitlog-to-changelog
+++ b/build-aux/gitlog-to-changelog
@@ -31,11 +31,11 @@
 # are valid code in both sh and perl.  When executed by sh, they re-execute
 # the script through the perl program found in $PATH.  The '-x' option
 # is essential as well; without it, perl would re-execute the script
-# through /bin/sh.  When executed by  perl, the next two lines are a no-op.
+# through /bin/sh.  When executed by perl, the next two lines are a no-op.
 eval 'exec perl -wSx "$0" "$@"'
      if 0;
 
-my $VERSION = '2018-03-07 03:47'; # UTC
+my $VERSION = '2020-04-04 15:07'; # UTC
 # The definition above must lie within the first 8 lines in order
 # for the Emacs time-stamp write hook (at end) to update it.
 # If you change this file with Emacs, please let the write hook
diff --git a/build-aux/update-copyright b/build-aux/update-copyright
index 4f79b56be78..d9b7f683a08 100755
--- a/build-aux/update-copyright
+++ b/build-aux/update-copyright
@@ -133,11 +133,11 @@
 # are valid code in both sh and perl.  When executed by sh, they re-execute
 # the script through the perl program found in $PATH.  The '-x' option
 # is essential as well; without it, perl would re-execute the script
-# through /bin/sh.  When executed by  perl, the next two lines are a no-op.
+# through /bin/sh.  When executed by perl, the next two lines are a no-op.
 eval 'exec perl -wSx -0777 -pi "$0" "$@"'
      if 0;
 
-my $VERSION = '2018-03-07.03:47'; # UTC
+my $VERSION = '2020-04-04.15:07'; # UTC
 # The definition above must lie within the first 8 lines in order
 # for the Emacs time-stamp write hook (at end) to update it.
 # If you change this file with Emacs, please let the write hook