Use kPointerSize when cross-compiling. am: b6c230117d am: 2f7444b38d am: 1cce663b32

Original change: https://android-review.googlesource.com/c/platform/art/+/2402709

Change-Id: I0a537b7771c55414ae77dc1eff859b5bd973ee94
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>