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/.

tools/snippet/warn-on-use.h

@@ -0,0 +1,109 @@
+/* A C macro for emitting warnings if a function is used.
+   Copyright (C) 2010-2012 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 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
+   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/>.  */
+
+/* _GL_WARN_ON_USE (function, "literal string") issues a declaration
+   for FUNCTION which will then trigger a compiler warning containing
+   the text of "literal string" anywhere that function is called, if
+   supported by the compiler.  If the compiler does not support this
+   feature, the macro expands to an unused extern declaration.
+
+   This macro is useful for marking a function as a potential
+   portability trap, with the intent that "literal string" include
+   instructions on the replacement function that should be used
+   instead.  However, one of the reasons that a function is a
+   portability trap is if it has the wrong signature.  Declaring
+   FUNCTION with a different signature in C is a compilation error, so
+   this macro must use the same type as any existing declaration so
+   that programs that avoid the problematic FUNCTION do not fail to
+   compile merely because they included a header that poisoned the
+   function.  But this implies that _GL_WARN_ON_USE is only safe to
+   use if FUNCTION is known to already have a declaration.  Use of
+   this macro implies that there must not be any other macro hiding
+   the declaration of FUNCTION; but undefining FUNCTION first is part
+   of the poisoning process anyway (although for symbols that are
+   provided only via a macro, the result is a compilation error rather
+   than a warning containing "literal string").  Also note that in
+   C++, it is only safe to use if FUNCTION has no overloads.
+
+   For an example, it is possible to poison 'getline' by:
+   - adding a call to gl_WARN_ON_USE_PREPARE([[#include <stdio.h>]],
+     [getline]) in configure.ac, which potentially defines
+     HAVE_RAW_DECL_GETLINE
+   - adding this code to a header that wraps the system <stdio.h>:
+     #undef getline
+     #if HAVE_RAW_DECL_GETLINE
+     _GL_WARN_ON_USE (getline, "getline is required by POSIX 2008, but"
+       "not universally present; use the gnulib module getline");
+     #endif
+
+   It is not possible to directly poison global variables.  But it is
+   possible to write a wrapper accessor function, and poison that
+   (less common usage, like &environ, will cause a compilation error
+   rather than issue the nice warning, but the end result of informing
+   the developer about their portability problem is still achieved):
+   #if HAVE_RAW_DECL_ENVIRON
+   static inline char ***rpl_environ (void) { return &environ; }
+   _GL_WARN_ON_USE (rpl_environ, "environ is not always properly declared");
+   # undef environ
+   # define environ (*rpl_environ ())
+   #endif
+   */
+#ifndef _GL_WARN_ON_USE
+
+# if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__)
+/* A compiler attribute is available in gcc versions 4.3.0 and later.  */
+#  define _GL_WARN_ON_USE(function, message) \
+extern __typeof__ (function) function __attribute__ ((__warning__ (message)))
+# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
+/* Verify the existence of the function.  */
+#  define _GL_WARN_ON_USE(function, message) \
+extern __typeof__ (function) function
+# else /* Unsupported.  */
+#  define _GL_WARN_ON_USE(function, message) \
+_GL_WARN_EXTERN_C int _gl_warn_on_use
+# endif
+#endif
+
+/* _GL_WARN_ON_USE_CXX (function, rettype, parameters_and_attributes, "string")
+   is like _GL_WARN_ON_USE (function, "string"), except that the function is
+   declared with the given prototype, consisting of return type, parameters,
+   and attributes.
+   This variant is useful for overloaded functions in C++. _GL_WARN_ON_USE does
+   not work in this case.  */
+#ifndef _GL_WARN_ON_USE_CXX
+# if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__)
+#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
+extern rettype function parameters_and_attributes \
+     __attribute__ ((__warning__ (msg)))
+# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
+/* Verify the existence of the function.  */
+#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
+extern rettype function parameters_and_attributes
+# else /* Unsupported.  */
+#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
+_GL_WARN_EXTERN_C int _gl_warn_on_use
+# endif
+#endif
+
+/* _GL_WARN_EXTERN_C declaration;
+   performs the declaration with C linkage.  */
+#ifndef _GL_WARN_EXTERN_C
+# if defined __cplusplus
+#  define _GL_WARN_EXTERN_C extern "C"
+# else
+#  define _GL_WARN_EXTERN_C extern
+# endif
+#endif