gnulib: upgrade to today's version

* tools/snippet/_Noreturn.h, tools/snippet/c++defs.h,
tools/snippet/arg-nonnull.h, tools/snippet/warn-on-use.h: Rename to...
* lib/_Noreturn.h, lib/c++defs.h, lib/arg-nonnull.h,
lib/warn-on-use.h: ... these.
* lib/filename.h, lib/getopt-cdefs.in.h, lib/getopt-core.h,
lib/getopt-ext.h, lib/getopt-pfx-core.h, lib/getopt-pfx-ext.h,
lib/localtime-buffer.c, lib/localtime-buffer.h, lib/malloca.c,
lib/malloca.h, lib/malloca.valgrind, lib/stat-w32.c, lib/stat-w32.h,
m4/eealloc.m4, m4/localtime-buffer.m4, m4/malloca.m4: New files.
* lib/argp-help.c, lib/argp-parse.c, lib/error.c, lib/float.in.h,
lib/getopt1.c, lib/getopt.c, lib/getopt.in.h, lib/getopt_int.h,
lib/gettext.h, lib/gettimeofday.c, lib/intprops.h, lib/isatty.c,
lib/limits.in.h, lib/localcharset.c, lib/Makefile.am, lib/mbrtowc.c,
lib/mbsinit.c, lib/msvc-nothrow.c, lib/quotearg.c, lib/stat.c,
lib/stdalign.in.h, lib/stdint.in.h, lib/string.in.h,
lib/sys_stat.in.h, lib/sys_types.in.h, lib/tempname.c, lib/time.in.h,
lib/unistd.in.h, lib/vasnprintf.c, lib/wchar.in.h, lib/wctype.in.h,
lib/xalloc.h, lib/xalloc-oversized.h, m4/fcntl-o.m4, m4/float_h.m4,
m4/getopt.m4, m4/gettimeofday.m4, m4/gnulib-common.m4,
m4/gnulib-comp.m4, m4/include_next.m4, m4/largefile.m4, m4/lstat.m4,
m4/mbrtowc.m4, m4/memchr.m4, m4/mkstemp.m4, m4/printf.m4, m4/sleep.m4,
m4/stat.m4, m4/stdalign.m4, m4/stdint.m4, m4/strerror.m4,
m4/string_h.m4, m4/sys_stat_h.m4, m4/sys_time_h.m4, m4/sys_types_h.m4,
m4/time_h.m4, m4/unistd_h.m4, m4/wchar_h.m4, m4/wctype_h.m4,
m4/wint_t.m4: Update.

lib/getopt-cdefs.in.h

@@ -0,0 +1,67 @@
+/* getopt-on-non-glibc compatibility macros.
+   Copyright (C) 1989-2017 Free Software Foundation, Inc.
+   This file is part of gnulib.
+   Unlike most of the getopt implementation, it is NOT shared
+   with the GNU C Library.
+
+   gnulib is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 3 of
+   the License, or (at your option) any later version.
+
+   gnulib is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with gnulib; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _GETOPT_CDEFS_H
+#define _GETOPT_CDEFS_H 1
+
+/* This header should not be used directly; include getopt.h or
+   unistd.h instead.  It does not have a protective #error, because
+   the guard macro for getopt.h in gnulib is not fixed.  */
+
+/* getopt-core.h and getopt-ext.h are shared with GNU libc, and expect
+   a number of the internal macros supplied to GNU libc's headers by
+   sys/cdefs.h.  Provide fallback definitions for all of them.  */
+#if @HAVE_SYS_CDEFS_H@
+# include <sys/cdefs.h>
+#endif
+
+#ifndef __BEGIN_DECLS
+# ifdef __cplusplus
+#  define __BEGIN_DECLS extern "C" {
+# else
+#  define __BEGIN_DECLS /* nothing */
+# endif
+#endif
+#ifndef __END_DECLS
+# ifdef __cplusplus
+#  define __END_DECLS }
+# else
+#  define __END_DECLS /* nothing */
+# endif
+#endif
+
+#ifndef __GNUC_PREREQ
+# if defined __GNUC__ && defined __GNUC_VERSION__
+# define __GNUC_PREREQ(maj, min) \
+        ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
+# else
+#  define __GNUC_PREREQ(maj, min) 0
+# endif
+#endif
+
+#ifndef __THROW
+# if defined __cplusplus && __GNUC_PREREQ (2,8)
+#  define __THROW       throw ()
+# else
+#  define __THROW
+# endif
+#endif
+
+#endif /* _GETOPT_CDEFS_H */