Fix terminal detection (#32)

Change from syscall.Stdout to os.Stdout.Fd().

README.md

@@ -1,5 +1,5 @@
 ## log
-<img align="right" src="https://raw.githubusercontent.com/go-playground/log/master/logo.png">![Project status](https://img.shields.io/badge/version-7.0.0-green.svg)
+<img align="right" src="https://raw.githubusercontent.com/go-playground/log/master/logo.png">![Project status](https://img.shields.io/badge/version-7.0.1-green.svg)
 [![Build Status](https://travis-ci.org/go-playground/log.svg?branch=master)](https://travis-ci.org/go-playground/log)
 [![Coverage Status](https://coveralls.io/repos/github/go-playground/log/badge.svg?branch=master)](https://coveralls.io/github/go-playground/log?branch=master)
 [![Go Report Card](https://goreportcard.com/badge/github.com/go-playground/log)](https://goreportcard.com/report/github.com/go-playground/log)

log.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"os"
 	"sync"
-	"syscall"
 	"time"
 
 	"golang.org/x/crypto/ssh/terminal"
@@ -21,7 +20,7 @@ var (
 )
 
 func init() {
-	if terminal.IsTerminal(syscall.Stdout) {
+	if terminal.IsTerminal(int(os.Stdout.Fd())) {
 		defaultHandler = newDefaultLogger()
 		AddHandler(defaultHandler, AllLevels...)
 		defaultHandlerRegistered = true