net: do not set SO_REUSEADDR for windows

Fixes #2307.

R=golang-dev, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/5306049

src/pkg/net/sock_windows.go

@@ -11,9 +11,6 @@ import (
 )
 
 func setKernelSpecificSockopt(s syscall.Handle, f int) {
-	// Allow reuse of recently-used addresses and ports.
-	syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
-
 	// Allow broadcast.
 	syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1)