RFR: JDK-8056934: ZipInputStream does not correctly handle local header data descriptors with the optional signature missing

[Martin Buchholz]

Hi Xueming and Alan,

I'd like you to do a code review.

https://bugs.openjdk.java.net/browse/JDK-8056934
http://cr.openjdk.java.net/~martin/webrevs/openjdk9/zip-DataDescriptorSignatureMissing/

This seems like an atypical off-by-one, so I'm not sure how it happened,
and I have the nagging feeling I'm missing something.

Greg, this java code review contains a python program!