Merge "libsnapshot: Check for valid snapshots based on current slot" into main am: acdc4848

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2701654



Change-Id: Ia9abf433765b28a9f590f01c2fbf3d1be9f3a696
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>