Merge "snapuserd: Lock the buffer during snapshot-merge" into main am: e10fc836 am: 53741292

Original change: https://android-review.googlesource.com/c/platform/system/core/+/3368179



Change-Id: Iab03d147477774062cdf88af1f819bd8a2bf57c5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>