Merge "Prevent integer overflow in copyString" into sc-dev am: c5b18be73c am: e639c7b79b

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/expat/+/18587609

Change-Id: I31e08a61ffb43966de68cc48ecad04f624e1847d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>