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

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-DataDescriptorSignat... 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!