Fix zip64 reader when file size is < 4GB and 32 bit fields are -1

When CopyFrom writes a zipentry, it strips extra fields and generates
data descriptors. When writing data descriptors, it only writes 64 bit
values if the relevant sizes are >4GB. In some cases, the sizes are <4GB
but 32 bit sizes are set to -1. In this situation, CopyFrom will write
incorrect local file header, resulting in a zip file that can't be
parsed by standard zip tools.

Test: Unit Tests
Bug: 161922066
Change-Id: I64319a80647013eaf7693cf8bf5c6120016913a3