[Scudo] Improve ScopedString constructor am: 04f3ad960c am: bd8e39ab56 am: 70111cb7b7 am: 676fda1d5d

Original change: https://android-review.googlesource.com/c/platform/external/scudo/+/1729757

Change-Id: I8945218d380b8eaf40b147d44e4a3baf5a425724