Really add wcwidth.m4.

m4/wcwidth.m4

@@ -0,0 +1,26 @@
+# wcwidth.m4 serial 3
+dnl Copyright (C) 2006 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_WCWIDTH],
+[
+  dnl Persuade glibc <wchar.h> to declare wcwidth().
+  AC_REQUIRE([AC_GNU_SOURCE])
+
+  AC_REQUIRE([AC_C_INLINE])
+  AC_REQUIRE([gt_TYPE_WCHAR_T])
+
+  AC_CHECK_HEADERS_ONCE([wchar.h wctype.h])
+  AC_CHECK_FUNCS_ONCE([iswprint wcwidth])
+
+  AC_CHECK_DECLS([wcwidth], [], [], [
+/* AIX 3.2.5 declares wcwidth in <string.h>. */
+#if HAVE_STRING_H
+# include <string.h>
+#endif
+#if HAVE_WCHAR_H
+# include <wchar.h>
+#endif
+])])