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/unistd.in.h

@@ -127,11 +127,18 @@
 # include <sys/types.h>
 #endif
 
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
+/* The definition of _GL_ARG_NONNULL is copied here.  */
+
+/* The definition of _GL_WARN_ON_USE is copied here.  */
+
+
 /* Get getopt(), optarg, optind, opterr, optopt.
    But avoid namespace pollution on glibc systems.  */
 #if @GNULIB_UNISTD_H_GETOPT@ && !defined __GLIBC__ && !defined _GL_SYSTEM_GETOPT
-# define __need_getopt
-# include <getopt.h>
+# include <getopt-cdefs.h>
+# include <getopt-pfx-core.h>
 #endif
 
 #ifndef _GL_INLINE_HEADER_BEGIN
@@ -142,13 +149,6 @@ _GL_INLINE_HEADER_BEGIN
 # define _GL_UNISTD_INLINE _GL_INLINE
 #endif
 
-/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
-
-/* The definition of _GL_ARG_NONNULL is copied here.  */
-
-/* The definition of _GL_WARN_ON_USE is copied here.  */
-
-
 /* Hide some function declarations from <winsock2.h>.  */
 
 #if @GNULIB_GETHOSTNAME@ && @UNISTD_H_HAVE_WINSOCK2_H@
@@ -1457,6 +1457,36 @@ _GL_WARN_ON_USE (symlinkat, "symlinkat is not portable - "
 #endif
 
 
+#if @GNULIB_TRUNCATE@
+/* Change the size of the file designated by FILENAME to become equal to LENGTH.
+   Return 0 if successful, otherwise -1 and errno set.
+   See the POSIX:2008 specification
+   <http://pubs.opengroup.org/onlinepubs/9699919799/functions/truncate.html>.  */
+# if @REPLACE_TRUNCATE@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef truncate
+#   define truncate rpl_truncate
+#  endif
+_GL_FUNCDECL_RPL (truncate, int, (const char *filename, off_t length)
+                                 _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (truncate, int, (const char *filename, off_t length));
+# else
+#  if !@HAVE_TRUNCATE@
+_GL_FUNCDECL_SYS (truncate, int, (const char *filename, off_t length)
+                                 _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (truncate, int, (const char *filename, off_t length));
+# endif
+_GL_CXXALIASWARN (truncate);
+#elif defined GNULIB_POSIXCHECK
+# undef truncate
+# if HAVE_RAW_DECL_TRUNCATE
+_GL_WARN_ON_USE (truncate, "truncate is unportable - "
+                 "use gnulib module truncate for portability");
+# endif
+#endif
+
+
 #if @GNULIB_TTYNAME_R@
 /* Store at most BUFLEN characters of the pathname of the terminal FD is
    open on in BUF.  Return 0 on success, otherwise an error number.  */