Merge "Fix overflow sanitizer in copyWithAuthor." am: 18977849

    *(int*) (buffer + sizeof(entry) + sizeof(HistTsEntry)) = author;

    // Update lengths

    buffer[offsetof(entry, length)] = sizeof(HistTsEntryWithAuthor);

    buffer[sizeof(buffer) + Entry::kPreviousLengthOffset] = sizeof(HistTsEntryWithAuthor);

    buffer[offsetof(entry, data) + sizeof(HistTsEntryWithAuthor) + offsetof(ending, length)]

        = sizeof(HistTsEntryWithAuthor);

    // Write new buffer into FIFO

    dst->write(buffer, sizeof(buffer));

    return EntryIterator(mEntry).next();