Update Gnulib to v0.1-4379-g2ef5a9b4b

Also bump required autoconf version to 2.64, as required by Gnulib.

lib/libc-config.h

@@ -0,0 +1,189 @@
+/* System definitions for code taken from the GNU C Library
+
+   Copyright 2017-2021 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   This program 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this program; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert.  */
+
+/* This is intended to be a good-enough substitute for glibc system
+   macros like those defined in <sys/cdefs.h>, so that Gnulib code
+   shared with glibc can do this as the first #include:
+
+     #ifndef _LIBC
+     # include <libc-config.h>
+     #endif
+
+   When compiled as part of glibc this is a no-op; when compiled as
+   part of Gnulib this includes Gnulib's <config.h> and defines macros
+   that glibc library code would normally assume.  */
+
+#include <config.h>
+
+/* On glibc this includes <features.h> and <sys/cdefs.h> and #defines
+   _FEATURES_H, __WORDSIZE, and __set_errno.  On FreeBSD 11 it
+   includes <sys/cdefs.h> which defines __nonnull.  Elsewhere it
+   is harmless.  */
+#include <errno.h>
+
+/* From glibc <errno.h>.  */
+#ifndef __set_errno
+# define __set_errno(val) (errno = (val))
+#endif
+
+/* From glibc <features.h>.  */
+
+#ifndef __GNUC_PREREQ
+# if defined __GNUC__ && defined __GNUC_MINOR__
+#  define __GNUC_PREREQ(maj, min) ((maj) < __GNUC__ + ((min) <= __GNUC_MINOR__))
+# else
+#  define __GNUC_PREREQ(maj, min) 0
+# endif
+#endif
+
+#ifndef __glibc_clang_prereq
+# if defined __clang_major__ && defined __clang_minor__
+#  ifdef __apple_build_version__
+/* Apple for some reason renumbers __clang_major__ and __clang_minor__.
+   Gnulib code uses only __glibc_clang_prereq (3, 5); map it to
+   6000000 <= __apple_build_version__.  Support for other calls to
+   __glibc_clang_prereq can be added here as needed.  */
+#   define __glibc_clang_prereq(maj, min) \
+      ((maj) == 3 && (min) == 5 ? 6000000 <= __apple_build_version__ : 0)
+#  else
+#   define __glibc_clang_prereq(maj, min) \
+      ((maj) < __clang_major__ + ((min) <= __clang_minor__))
+#  endif
+# else
+#  define __glibc_clang_prereq(maj, min) 0
+# endif
+#endif
+
+#ifndef __attribute_maybe_unused__
+/* <sys/cdefs.h> either does not exist, or is too old for Gnulib.
+   Prepare to include <cdefs.h>, which is Gnulib's version of a
+   more-recent glibc <sys/cdefs.h>.  */
+
+/* Define _FEATURES_H so that <cdefs.h> does not include <features.h>.  */
+# ifndef _FEATURES_H
+#  define _FEATURES_H 1
+# endif
+/* Define __WORDSIZE so that <cdefs.h> does not attempt to include
+   nonexistent files.  Make it a syntax error, since Gnulib does not
+   use __WORDSIZE now, and if Gnulib uses it later the syntax error
+   will let us know that __WORDSIZE needs configuring.  */
+# ifndef __WORDSIZE
+#  define __WORDSIZE %%%
+# endif
+/* Undef the macros unconditionally defined by our copy of glibc
+   <sys/cdefs.h>, so that they do not clash with any system-defined
+   versions.  */
+# undef _SYS_CDEFS_H
+# undef __ASMNAME
+# undef __ASMNAME2
+# undef __BEGIN_DECLS
+# undef __CONCAT
+# undef __END_DECLS
+# undef __HAVE_GENERIC_SELECTION
+# undef __LDBL_COMPAT
+# undef __LDBL_REDIR
+# undef __LDBL_REDIR1
+# undef __LDBL_REDIR1_DECL
+# undef __LDBL_REDIR1_NTH
+# undef __LDBL_REDIR2_DECL
+# undef __LDBL_REDIR_DECL
+# undef __LDBL_REDIR_NTH
+# undef __LEAF
+# undef __LEAF_ATTR
+# undef __NTH
+# undef __NTHNL
+# undef __REDIRECT
+# undef __REDIRECT_LDBL
+# undef __REDIRECT_NTH
+# undef __REDIRECT_NTHNL
+# undef __REDIRECT_NTH_LDBL
+# undef __STRING
+# undef __THROW
+# undef __THROWNL
+# undef __attr_access
+# undef __attribute__
+# undef __attribute_alloc_size__
+# undef __attribute_artificial__
+# undef __attribute_const__
+# undef __attribute_deprecated__
+# undef __attribute_deprecated_msg__
+# undef __attribute_format_arg__
+# undef __attribute_format_strfmon__
+# undef __attribute_malloc__
+# undef __attribute_noinline__
+# undef __attribute_nonstring__
+# undef __attribute_pure__
+# undef __attribute_returns_twice__
+# undef __attribute_used__
+# undef __attribute_warn_unused_result__
+# undef __bos
+# undef __bos0
+# undef __errordecl
+# undef __extension__
+# undef __extern_always_inline
+# undef __extern_inline
+# undef __flexarr
+# undef __fortify_function
+# undef __glibc_c99_flexarr_available
+# undef __glibc_has_attribute
+# undef __glibc_has_builtin
+# undef __glibc_has_extension
+# undef __glibc_macro_warning
+# undef __glibc_macro_warning1
+# undef __glibc_objsize
+# undef __glibc_objsize0
+# undef __glibc_unlikely
+# undef __inline
+# undef __ptr_t
+# undef __restrict
+# undef __restrict_arr
+# undef __va_arg_pack
+# undef __va_arg_pack_len
+# undef __warnattr
+
+/* Include our copy of glibc <sys/cdefs.h>.  */
+# include <cdefs.h>
+
+/* <cdefs.h> __inline is too pessimistic for non-GCC.  */
+# undef __inline
+# ifndef HAVE___INLINE
+#  if 199901 <= __STDC_VERSION__ || defined inline
+#   define __inline inline
+#  else
+#   define __inline
+#  endif
+# endif
+
+#endif /* defined __glibc_likely */
+
+
+/* A substitute for glibc <libc-symbols.h>, good enough for Gnulib.  */
+#define attribute_hidden
+#define libc_hidden_proto(name)
+#define libc_hidden_def(name)
+#define libc_hidden_weak(name)
+#define libc_hidden_ver(local, name)
+#define strong_alias(name, aliasname)
+#define weak_alias(name, aliasname)
+
+/* A substitute for glibc <shlib-compat.h>, good enough for Gnulib.  */
+#define SHLIB_COMPAT(lib, introduced, obsoleted) 0
+#define compat_symbol(lib, local, symbol, version) extern int dummy
+#define versioned_symbol(lib, local, symbol, version) extern int dummy