mkrunetype: install a Makefile and tweak it slightly so it can be built.

R=rsc
CC=golang-dev
https://golang.org/cl/2813041

src/lib9/utf/Makefile

+# Copyright 2010 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+# The library is built by the Makefile in the parent directory.
+# This Makefile only builds mkrunetype.
+
+include ../../Make.inc
+O:=$(HOST_O)
+
+TARG=mkrunetype
+
+OFILES=\
+	mkrunetype.$O\
+
+include ../../Make.ccmd

src/lib9/utf/mkrunetype.c

@@ -32,11 +32,9 @@
  * isdigitrune is true iff c is a numeric-digit category.
  */
 
+#include <u.h>
+#include <libc.h>
 #include <stdio.h>
-#include <stdlib.h>
-#include <stdarg.h>
-#include <string.h>
-#include <libgen.h>
 #include "utf.h"
 #include "utfdef.h"
 
@@ -588,8 +586,7 @@ mkisronly(const char* label, char* prop) {
 static void
 mktables(char *src, int usepairs)
 {
-	printf("/* generated automatically by mkrunetype.c from %s */\n\n",
-		basename(src));
+	printf("/* generated automatically by mkrunetype.c from %s */\n\n", src);
 
 	/*
 	 * we special case the space and digit tables, since they are assumed