func xsamefile(f1, f2 string) bool {
	fi1, err1 := os.Stat(f1)
	fi2, err2 := os.Stat(f2)
	if err1 != nil || err2 != nil {
		return f1 == f2
	}
	return os.SameFile(fi1, fi2)
}

func xgetgoarm() string {
	// If we're building on an actual arm system, and not building
	// a cross-compiling toolchain, try to exec ourselves
	// to detect whether VFP is supported and set the default GOARM.

	b = os.Getenv("GOOS")
	if b == "" {
		b = gohostos
	}
	goos = b
	if find(goos, okgoos) < 0 {
		fatalf("unknown $GOOS %s", goos)
	}

	b = os.Getenv("GOARM")
	if b == "" {
		b = xgetgoarm()
	}
	goarm = b

	b = os.Getenv("GOARM64")
	if b == "" {
		b = "v8.0"
	}
	goarm64 = b

	b = os.Getenv("GO386")
	if b == "" {
		b = "sse2"
	}
	go386 = b