code review 4657074: os: fix build for Plan 9

src/pkg/os/file_plan9.go

 // Copyright 2011 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.
 
 package os
 
 import (
         "runtime"
-        "sync"
         "syscall"
 )
 
 // File represents an open file descriptor.
 type File struct {
         fd      int
         name    string
-        dirinfo *dirInfo   // nil unless directory being read
-        nepipe  int        // number of consecutive EPIPE in Write
-        l       sync.Mutex // used to implement windows pread/pwrite

[brainman, 2011/07/05 05:11:42]

This lock is for windows only. I don't think you need it. If you agree, perhaps,
you could change file_unix.go file as well. Thank you.

+        dirinfo *dirInfo // nil unless directory being read
+        nepipe  int      // number of consecutive EPIPE in Write
 }
 
 // Fd returns the integer Unix file descriptor referencing the open file.
 func (file *File) Fd() int {
         if file == nil {
                 return -1
         }
         return file.fd
 }
 
@@ skipping 311 matching lines @@
         return EPLAN9
 }
 
 func Lchown(name string, uid, gid int) Error {
         return EPLAN9
 }
 
 func (f *File) Chown(uid, gid int) Error {
         return EPLAN9
 }