Merge "libsnapshot: Fix CowWriter::Finalize() not restoring footer correctly." am: ccc7db3d92

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1630126

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I376bf6ffa4b39a090bd0413989f6fc662e73e051