Update gnulib.

* lib/Makefile.am, lib/alloca.in.h, lib/argmatch.c, lib/argmatch.h,
lib/argp-ba.c, lib/argp-eexst.c, lib/argp-fmtstream.c,
lib/argp-fmtstream.h, lib/argp-fs-xinl.c, lib/argp-help.c,
lib/argp-namefrob.h, lib/argp-parse.c, lib/argp-pin.c, lib/argp-pv.c,
lib/argp-pvh.c, lib/argp-xinl.c, lib/argp.h, lib/asnprintf.c,
lib/basename-lgpl.c, lib/c-ctype.c, lib/c-ctype.h, lib/c-strcase.h,
lib/c-strcasecmp.c, lib/c-strcaseeq.h, lib/c-strncasecmp.c,
lib/config.charset, lib/dirname-lgpl.c, lib/dirname.h, lib/dosname.h,
lib/errno.in.h, lib/error.c, lib/error.h, lib/exitfail.c,
lib/exitfail.h, lib/fcntl.in.h, lib/float+.h, lib/float.c,
lib/float.in.h, lib/getopt.c, lib/getopt.in.h, lib/getopt1.c,
lib/getopt_int.h, lib/gettext.h, lib/gettimeofday.c, lib/intprops.h,
lib/isatty.c, lib/itold.c, lib/localcharset.c, lib/localcharset.h,
lib/lstat.c, lib/malloc.c, lib/mbrtowc.c, lib/mbsinit.c, lib/memchr.c,
lib/mempcpy.c, lib/mkstemp.c, lib/mkstemps.c, lib/msvc-inval.c,
lib/msvc-inval.h, lib/msvc-nothrow.c, lib/msvc-nothrow.h, lib/pathmax.h,
lib/printf-args.c, lib/printf-args.h, lib/printf-parse.c,
lib/printf-parse.h, lib/progname.c, lib/progname.h, lib/quote.h,
lib/quotearg.c, lib/quotearg.h, lib/rawmemchr.c, lib/ref-add.sin,
lib/ref-del.sin, lib/secure_getenv.c, lib/size_max.h, lib/sleep.c,
lib/stat.c, lib/stdalign.in.h, lib/stdbool.in.h, lib/stddef.in.h,
lib/stdint.in.h, lib/stdio.in.h, lib/stdlib.in.h, lib/stpcpy.c,
lib/strcasecmp.c, lib/strchrnul.c, lib/streq.h, lib/strerror-override.c,
lib/strerror-override.h, lib/strerror.c, lib/string.in.h,
lib/strings.in.h, lib/stripslash.c, lib/strncasecmp.c, lib/strndup.c,
lib/strnlen.c, lib/strverscmp.c, lib/sys_stat.in.h, lib/sys_time.in.h,
lib/sys_types.in.h, lib/sys_wait.in.h, lib/sysexits.in.h,
lib/tempname.c, lib/tempname.h, lib/time.in.h, lib/unistd.c,
lib/unistd.in.h, lib/vasnprintf.c, lib/vasnprintf.h, lib/verify.h,
lib/vsnprintf.c, lib/wchar.in.h, lib/wctype.in.h, lib/xalloc-die.c,
lib/xalloc-oversized.h, lib/xalloc.h, lib/xmalloc.c, lib/xsize.h,
m4/00gnulib.m4, m4/absolute-header.m4, m4/alloca.m4, m4/argp.m4,
m4/codeset.m4, m4/configmake.m4, m4/dirname.m4, m4/double-slash-root.m4,
m4/errno_h.m4, m4/error.m4, m4/exponentd.m4, m4/extensions.m4,
m4/extern-inline.m4, m4/fcntl-o.m4, m4/fcntl_h.m4, m4/float_h.m4,
m4/getopt.m4, m4/gettimeofday.m4, m4/glibc21.m4, m4/gnulib-cache.m4,
m4/gnulib-common.m4, m4/gnulib-comp.m4, m4/gnulib-tool.m4,
m4/include_next.m4, m4/intmax_t.m4, m4/inttypes_h.m4, m4/isatty.m4,
m4/largefile.m4, m4/localcharset.m4, m4/locale-fr.m4, m4/locale-ja.m4,
m4/locale-zh.m4, m4/longlong.m4, m4/lstat.m4, m4/malloc.m4,
m4/math_h.m4, m4/mbrtowc.m4, m4/mbsinit.m4, m4/mbstate_t.m4,
m4/memchr.m4, m4/mempcpy.m4, m4/mkstemp.m4, m4/mkstemps.m4,
m4/mmap-anon.m4, m4/msvc-inval.m4, m4/msvc-nothrow.m4, m4/multiarch.m4,
m4/nocrash.m4, m4/off_t.m4, m4/pathmax.m4, m4/printf.m4, m4/quote.m4,
m4/quotearg.m4, m4/rawmemchr.m4, m4/secure_getenv.m4, m4/size_max.m4,
m4/sleep.m4, m4/ssize_t.m4, m4/stat.m4, m4/stdalign.m4, m4/stdbool.m4,
m4/stddef_h.m4, m4/stdint.m4, m4/stdint_h.m4, m4/stdio_h.m4,
m4/stdlib_h.m4, m4/stpcpy.m4, m4/strcase.m4, m4/strchrnul.m4,
m4/strerror.m4, m4/string_h.m4, m4/strings_h.m4, m4/strndup.m4,
m4/strnlen.m4, m4/strverscmp.m4, m4/sys_socket_h.m4, m4/sys_stat_h.m4,
m4/sys_time_h.m4, m4/sys_types_h.m4, m4/sys_wait_h.m4, m4/sysexits.m4,
m4/tempname.m4, m4/time_h.m4, m4/unistd_h.m4, m4/vasnprintf.m4,
m4/vsnprintf.m4, m4/warn-on-use.m4, m4/wchar_h.m4, m4/wchar_t.m4,
m4/wctype_h.m4, m4/wint_t.m4, m4/xalloc.m4, m4/xsize.m4,
tools/snippet/arg-nonnull.h, tools/snippet/c++defs.h,
tools/snippet/warn-on-use.h: Update.

lib/unistd.in.h

@@ -1,5 +1,5 @@
 /* Substitute for and wrapper around <unistd.h>.
-   Copyright (C) 2003-2013 Free Software Foundation, Inc.
+   Copyright (C) 2003-2015 Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -21,9 +21,23 @@
 #endif
 @PRAGMA_COLUMNS@
 
+#ifdef _GL_INCLUDING_UNISTD_H
+/* Special invocation convention:
+   - On Mac OS X 10.3.9 we have a sequence of nested includes
+     <unistd.h> -> <signal.h> -> <pthread.h> -> <unistd.h>
+     In this situation, the functions are not yet declared, therefore we cannot
+     provide the C++ aliases.  */
+
+#@INCLUDE_NEXT@ @NEXT_UNISTD_H@
+
+#else
+/* Normal invocation convention.  */
+
 /* The include_next requires a split double-inclusion guard.  */
 #if @HAVE_UNISTD_H@
+# define _GL_INCLUDING_UNISTD_H
 # @INCLUDE_NEXT@ @NEXT_UNISTD_H@
+# undef _GL_INCLUDING_UNISTD_H
 #endif
 
 /* Get all possible declarations of gethostname().  */
@@ -387,6 +401,12 @@ _GL_WARN_ON_USE (dup3, "dup3 is unportable - "
 /* Set of environment variables and values.  An array of strings of the form
    "VARIABLE=VALUE", terminated with a NULL.  */
 #  if defined __APPLE__ && defined __MACH__
+#   include <TargetConditionals.h>
+#   if !TARGET_OS_IPHONE && !TARGET_IPHONE_SIMULATOR
+#    define _GL_USE_CRT_EXTERNS
+#   endif
+#  endif
+#  ifdef _GL_USE_CRT_EXTERNS
 #   include <crt_externs.h>
 #   define environ (*_NSGetEnviron ())
 #  else
@@ -1273,13 +1293,24 @@ _GL_WARN_ON_USE (readlink, "readlink is unportable - "
 
 
 #if @GNULIB_READLINKAT@
-# if !@HAVE_READLINKAT@
+# if @REPLACE_READLINKAT@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define readlinkat rpl_readlinkat
+#  endif
+_GL_FUNCDECL_RPL (readlinkat, ssize_t,
+                  (int fd, char const *file, char *buf, size_t len)
+                  _GL_ARG_NONNULL ((2, 3)));
+_GL_CXXALIAS_RPL (readlinkat, ssize_t,
+                  (int fd, char const *file, char *buf, size_t len));
+# else
+#  if !@HAVE_READLINKAT@
 _GL_FUNCDECL_SYS (readlinkat, ssize_t,
                   (int fd, char const *file, char *buf, size_t len)
                   _GL_ARG_NONNULL ((2, 3)));
-# endif
+#  endif
 _GL_CXXALIAS_SYS (readlinkat, ssize_t,
                   (int fd, char const *file, char *buf, size_t len));
+# endif
 _GL_CXXALIASWARN (readlinkat);
 #elif defined GNULIB_POSIXCHECK
 # undef readlinkat
@@ -1393,13 +1424,25 @@ _GL_WARN_ON_USE (symlink, "symlink is not portable - "
 
 
 #if @GNULIB_SYMLINKAT@
-# if !@HAVE_SYMLINKAT@
+# if @REPLACE_SYMLINKAT@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef symlinkat
+#   define symlinkat rpl_symlinkat
+#  endif
+_GL_FUNCDECL_RPL (symlinkat, int,
+                  (char const *contents, int fd, char const *file)
+                  _GL_ARG_NONNULL ((1, 3)));
+_GL_CXXALIAS_RPL (symlinkat, int,
+                  (char const *contents, int fd, char const *file));
+# else
+#  if !@HAVE_SYMLINKAT@
 _GL_FUNCDECL_SYS (symlinkat, int,
                   (char const *contents, int fd, char const *file)
                   _GL_ARG_NONNULL ((1, 3)));
-# endif
+#  endif
 _GL_CXXALIAS_SYS (symlinkat, int,
                   (char const *contents, int fd, char const *file));
+# endif
 _GL_CXXALIASWARN (symlinkat);
 #elif defined GNULIB_POSIXCHECK
 # undef symlinkat
@@ -1539,4 +1582,5 @@ _GL_CXXALIASWARN (write);
 _GL_INLINE_HEADER_END
 
 #endif /* _@GUARD_PREFIX@_UNISTD_H */
+#endif /* _GL_INCLUDING_UNISTD_H */
 #endif /* _@GUARD_PREFIX@_UNISTD_H */