update_engine: fix 32bit system type error am: da3a49b919

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3225962

Change-Id: Ia9b4eb0418259fb87141921de4bdeb67f3a129b3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>