gnulib: Add modules argmatch and isatty.

* lib/argmatch.c, lib/argmatch.h, lib/c-ctype.c, lib/c-ctype.h,
lib/config.charset, lib/c-strcasecmp.c, lib/c-strcaseeq.h,
lib/c-strcase.h, lib/c-strncasecmp.c, lib/exitfail.c, lib/exitfail.h,
lib/isatty.c, lib/localcharset.c, lib/localcharset.h, lib/mbrtowc.c,
lib/mbsinit.c, lib/quotearg.c, lib/quotearg.h, lib/quote.h,
lib/ref-add.sin, lib/ref-del.sin, lib/streq.h, lib/wctype-h.c,
lib/wctype.in.h, lib/xalloc-die.c, lib/xalloc.h, lib/xalloc-oversized.h,
lib/xmalloc.c, m4/codeset.m4, m4/configmake.m4, m4/glibc21.m4,
m4/isatty.m4, m4/localcharset.m4, m4/locale-fr.m4, m4/locale-ja.m4,
m4/locale-zh.m4, m4/mbrtowc.m4, m4/mbsinit.m4, m4/mbstate_t.m4,
m4/quotearg.m4, m4/quote.m4, m4/wctype_h.m4, m4/xalloc.m4: New files.
* lib/Makefile.am, m4/gnulib-cache.m4, m4/gnulib-comp.m4: Update.

m4/glibc21.m4

@@ -0,0 +1,34 @@
+# glibc21.m4 serial 5
+dnl Copyright (C) 2000-2002, 2004, 2008, 2010-2013 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Test for the GNU C Library, version 2.1 or newer, or uClibc.
+# From Bruno Haible.
+
+AC_DEFUN([gl_GLIBC21],
+  [
+    AC_CACHE_CHECK([whether we are using the GNU C Library >= 2.1 or uClibc],
+      [ac_cv_gnu_library_2_1],
+      [AC_EGREP_CPP([Lucky],
+        [
+#include <features.h>
+#ifdef __GNU_LIBRARY__
+ #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 1) || (__GLIBC__ > 2)
+  Lucky GNU user
+ #endif
+#endif
+#ifdef __UCLIBC__
+ Lucky user
+#endif
+        ],
+        [ac_cv_gnu_library_2_1=yes],
+        [ac_cv_gnu_library_2_1=no])
+      ]
+    )
+    AC_SUBST([GLIBC21])
+    GLIBC21="$ac_cv_gnu_library_2_1"
+  ]
+)