[scudo] Untag BlockEnd in reallocate am: 5df4673efd am: 9f60e120b8 am: e41545ed1c am: 21edd09fb4

Original change: https://android-review.googlesource.com/c/platform/external/scudo/+/1763655

Change-Id: Iad29c23c0d80cc1536bcb647657646bd0cb6b37e