adjust zeroing to support more than 64 bits. Bug: b/156802687 Change-Id: I42448b4dd6d5c04143eb9075cd61317e115ed936 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/175564 Reviewed-by: Erik Varga <erikvarga@webrtc.org> Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Cr-Commit-Position: refs/heads/master@{#31300}