RFR: JDK-8073158 zip files with total entry count 0xFFFF need not be ZIP64 files

[Martin Buchholz]

Hi Xueming and Alan,

I'd like you to do a code review.

https://bugs.openjdk.java.net/browse/JDK-8073158
http://cr.openjdk.java.net/~martin/webrevs/openjdk9/0xffff-entries-zip-file/

Of course, the really correct thing is to have at most one zip
implementation per programming language, but I'm not trying to fix that
here (how many zip implementations does openjdk have?)