golang gccgo 代码
文件路径：/src/go/build/gccgo.go
/ Copyright 2018 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.
/go:build gccgo
package build
import "runtime"
/ getToolDir returns the default value of ToolDir.
func getToolDir() string {
return envOr("GCCGOTOOLDIR", runtime.GCCGOTOOLDIR)
}