Install gnulib to make sure we can use argp in ltlfilt.

* lib/Makefile.am, lib/alloca.c, lib/alloca.in.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/dirname-lgpl.c, lib/dirname.h, lib/dosname.h, lib/errno.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/intprops.h, lib/itold.c, lib/malloc.c, lib/memchr.c,
lib/memchr.valgrind, lib/mempcpy.c, lib/printf-args.c,
lib/printf-args.h, lib/printf-parse.c, lib/printf-parse.h,
lib/rawmemchr.c, lib/rawmemchr.valgrind, lib/size_max.h,
lib/sleep.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/strcasecmp.c,
lib/strchrnul.c, lib/strchrnul.valgrind, 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/sys_types.in.h, lib/sysexits.in.h,
lib/unistd.in.h, lib/vasnprintf.c, lib/vasnprintf.h, lib/verify.h,
lib/vsnprintf.c, lib/wchar.in.h, lib/xsize.h, m4/00gnulib.m4,
m4/alloca.m4, m4/argp.m4, m4/dirname.m4, m4/double-slash-root.m4,
m4/errno_h.m4, m4/exponentd.m4, m4/extensions.m4, m4/float_h.m4,
m4/getopt.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/longlong.m4, m4/malloc.m4,
m4/math_h.m4, m4/memchr.m4, m4/mempcpy.m4, m4/mmap-anon.m4,
m4/multiarch.m4, m4/nocrash.m4, m4/off_t.m4, m4/printf.m4,
m4/rawmemchr.m4, m4/size_max.m4, m4/sleep.m4, m4/ssize_t.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/strcase.m4,
m4/strchrnul.m4, m4/strerror.m4, m4/string_h.m4, m4/strings_h.m4,
m4/strndup.m4, m4/strnlen.m4, m4/sys_socket_h.m4, m4/sys_types_h.m4,
m4/sysexits.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/wint_t.m4,
m4/xsize.m4, tools/snippet/_Noreturn.h, tools/snippet/arg-nonnull.h,
tools/snippet/c++defs.h, tools/snippet/warn-on-use.h: New files from
gnulib 1af55d85d9762a679b4302d5995f05ccd883e956.
* configure.ac, Makefile.am: Adjust to compile gnulib.
* src/bin/Makefile.am: Adjust to use gnulib.
* README: Mention lib/.

lib/stddef.in.h

@@ -0,0 +1,86 @@
+/* A substitute for POSIX 2008 <stddef.h>, for platforms that have issues.
+
+   Copyright (C) 2009-2012 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
+   the Free Software Foundation; either version 3, 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Eric Blake.  */
+
+/*
+ * POSIX 2008 <stddef.h> for platforms that have issues.
+ * <http://www.opengroup.org/susv3xbd/stddef.h.html>
+ */
+
+#if __GNUC__ >= 3
+@PRAGMA_SYSTEM_HEADER@
+#endif
+@PRAGMA_COLUMNS@
+
+#if defined __need_wchar_t || defined __need_size_t  \
+  || defined __need_ptrdiff_t || defined __need_NULL \
+  || defined __need_wint_t
+/* Special invocation convention inside gcc header files.  In
+   particular, gcc provides a version of <stddef.h> that blindly
+   redefines NULL even when __need_wint_t was defined, even though
+   wint_t is not normally provided by <stddef.h>.  Hence, we must
+   remember if special invocation has ever been used to obtain wint_t,
+   in which case we need to clean up NULL yet again.  */
+
+# if !(defined _@GUARD_PREFIX@_STDDEF_H && defined _GL_STDDEF_WINT_T)
+#  ifdef __need_wint_t
+#   undef _@GUARD_PREFIX@_STDDEF_H
+#   define _GL_STDDEF_WINT_T
+#  endif
+#  @INCLUDE_NEXT@ @NEXT_STDDEF_H@
+# endif
+
+#else
+/* Normal invocation convention.  */
+
+# ifndef _@GUARD_PREFIX@_STDDEF_H
+
+/* The include_next requires a split double-inclusion guard.  */
+
+#  @INCLUDE_NEXT@ @NEXT_STDDEF_H@
+
+#  ifndef _@GUARD_PREFIX@_STDDEF_H
+#   define _@GUARD_PREFIX@_STDDEF_H
+
+/* On NetBSD 5.0, the definition of NULL lacks proper parentheses.  */
+#if @REPLACE_NULL@
+# undef NULL
+# ifdef __cplusplus
+   /* ISO C++ says that the macro NULL must expand to an integer constant
+      expression, hence '((void *) 0)' is not allowed in C++.  */
+#  if __GNUG__ >= 3
+    /* GNU C++ has a __null macro that behaves like an integer ('int' or
+       'long') but has the same size as a pointer.  Use that, to avoid
+       warnings.  */
+#   define NULL __null
+#  else
+#   define NULL 0L
+#  endif
+# else
+#  define NULL ((void *) 0)
+# endif
+#endif
+
+/* Some platforms lack wchar_t.  */
+#if !@HAVE_WCHAR_T@
+# define wchar_t int
+#endif
+
+#  endif /* _@GUARD_PREFIX@_STDDEF_H */
+# endif /* _@GUARD_PREFIX@_STDDEF_H */
+#endif /* __need_XXX */