String16::remove - avoid overflow am: 4048e499 am: 107f18cb am: 9be245c3...

String16::remove - avoid overflow am: 4048e499 am: 107f18cb am: 9be245c3 am: 64fb5012 am: 4e27b699 am: 26b81f59 am: 8367a666 am: 80c46b05 am: a5ef9c8e

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/11619802

Change-Id: Iac24c28df3d06530b9d9c14f5042aef40a8a3108