Import new gnulib.

m4/mbtowc.m4

@@ -0,0 +1,19 @@
+# mbtowc.m4 serial 2
+dnl Copyright (C) 2011-2013 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.
+
+AC_DEFUN([gl_FUNC_MBTOWC],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+
+  if false; then
+    REPLACE_MBTOWC=1
+  fi
+])
+
+# Prerequisites of lib/mbtowc.c.
+AC_DEFUN([gl_PREREQ_MBTOWC], [
+  :
+])