add missing Makefile to repair build

TBR=gri
OCL=28320
CL=28320

src/lib/go/Makefile

+# Copyright 2009 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.
+
+all: install
+
+GC=6g
+
+DIRS=\
+	ast \
+	doc \
+	parser \
+	scanner \
+	token \
+
+
+TEST=\
+	parser \
+	scanner \
+
+clean.dirs: $(addsuffix .clean, $(DIRS))
+install.dirs: $(addsuffix .install, $(DIRS))
+test.dirs: $(addsuffix .test, $(TEST))
+
+%.clean:
+	+cd $* && make clean
+
+%.install:
+	+cd $* && make install
+
+%.test:
+	+cd $* && make test
+
+clean: clean.dirs
+
+install: install.dirs
+
+test:	test.dirs
+
+# TODO: dependencies - should auto-generate
+
+scanner.install: token.install
+parser.install:	ast.install scanner.install token.install
+doc.install: ast.install token.install
+ast.install: token.install