make goyacc and units.y work again (minor tweaks).

document goyacc a little.

R=rsc
CC=go-dev
http://go/go-review/1017024

src/cmd/goyacc/Makefile

@@ -11,7 +11,7 @@ GOFILES=\
 include $(GOROOT)/src/Make.cmd
 
 units: goyacc units.y
-	goyacc units.y
+	./goyacc units.y
 	$(GC) y.go
 	$(LD) -o units y.$O
 

src/cmd/goyacc/doc.go

+// 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.
+
+/*
+
+The program goyacc is a version of yacc written in Go and generating
+as output a parser also in Go.
+
+It is largely transliterated from the Inferno version written in Limbo
+which in turn was largely transliterated from the Plan 9 version
+written in C and documented at
+
+	http://plan9.bell-labs.com/magic/man2html/1/yacc
+
+Yacc adepts will have no trouble adapting to this form of the tool.
+
+The file units.y in this directory is a yacc grammar for a version of
+the Unix tool units, also written in Go and largely transliterated
+from the Plan 9 C version.  
+
+*/
+package documentation

src/cmd/goyacc/goyacc.go

@@ -47,7 +47,6 @@ package main
 import
 (
 	"flag";
-	"io";
 	"fmt";
 	"bufio";
 	"os";
@@ -1472,8 +1471,6 @@ cpyact(curprod []int, max int)
 func
 openup()
 {
-	var buf string;
-
 	infile = flag.Arg(0);
 	finput = open(infile);
 	if(finput == nil) {

src/cmd/goyacc/units.y

@@ -26,7 +26,6 @@ package main
 import
 (
 	"flag";
-	"io";
 	"fmt";
 	"bufio";
 	"os";