Check boot image version before update. am: fd6640f792 am: f4ac457709 am: 23180fb19a am: 43a22b9ccc

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/1414692

Change-Id: I071e6435045e150608d32e40f8f5dd12a66afe59