fix update_engine warnings am: a75d5cbc92 am: 15b615ce91

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3419439

Change-Id: I76597e671d416e2699b3947b0ec0d909cf0df729
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>