os: use goarch.BigEndian

Change-Id: I83c23ae0933f6abe4c07144f69c3d9c18aece6e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/569175
Auto-Submit: Ian Lance Taylor <[email protected]>
Auto-Submit: Tobias Klauser <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>

Author: tklauser

src/os/dir_unix.go

@@ -7,6 +7,7 @@
 package os
 
 import (
+	"internal/goarch"
 	"io"
 	"runtime"
 	"sync"
@@ -153,7 +154,7 @@ func readInt(b []byte, off, size uintptr) (u uint64, ok bool) {
 	if len(b) < int(off+size) {
 		return 0, false
 	}
-	if isBigEndian {
+	if goarch.BigEndian {
 		return readIntBE(b[off:], size), true
 	}
 	return readIntLE(b[off:], size), true