Merge "libsnapshot: Implement OnlineKernelSnapshotWriter::OpenReader." am: b9795757e9 am: 7c1fafd7a0

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1434794

Change-Id: I9538f9670593ad2118fe098a9c266ea26f05434f