Import new gnulib.

m4/mbswidth.m4

@@ -0,0 +1,46 @@
+# mbswidth.m4 serial 18
+dnl Copyright (C) 2000-2002, 2004, 2006-2013 Free Software Foundation, 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.
+
+dnl autoconf tests required for use of mbswidth.c
+dnl From Bruno Haible.
+
+AC_DEFUN([gl_MBSWIDTH],
+[
+  AC_CHECK_HEADERS_ONCE([wchar.h])
+  AC_CHECK_FUNCS_ONCE([isascii mbsinit])
+
+  dnl UnixWare 7.1.1 <wchar.h> has a declaration of a function mbswidth()
+  dnl that clashes with ours.
+  AC_CACHE_CHECK([whether mbswidth is declared in <wchar.h>],
+    [ac_cv_have_decl_mbswidth],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[
+/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
+   <wchar.h>.
+   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included
+   before <wchar.h>.  */
+#include <stddef.h>
+#include <stdio.h>
+#include <time.h>
+#include <wchar.h>
+          ]],
+          [[
+  char *p = (char *) mbswidth;
+  return !p;
+          ]])],
+       [ac_cv_have_decl_mbswidth=yes],
+       [ac_cv_have_decl_mbswidth=no])])
+  if test $ac_cv_have_decl_mbswidth = yes; then
+    ac_val=1
+  else
+    ac_val=0
+  fi
+  AC_DEFINE_UNQUOTED([HAVE_DECL_MBSWIDTH_IN_WCHAR_H], [$ac_val],
+    [Define to 1 if you have a declaration of mbswidth() in <wchar.h>, and to 0 otherwise.])
+
+  AC_TYPE_MBSTATE_T
+])