archive/tar: use built-in clear to simplify code
Change-Id: I0e55dd68d92c39aba511b55368bf50d929d75f86
GitHub-Last-Rev:
17430140783db8bf3354304c8f28d6826186c6cb
GitHub-Pull-Request: golang/go#66158
Reviewed-on: https://go-review.googlesource.com/c/go/+/569696
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: qiulaidongfeng <2645477756@qq.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>