RFR(S): 8073497: Lazy conversion of ZipEntry time

[Claes Redestad]

Hi all,

please review this patch to re-introduce laziness in the java-to-dos time
conversions for the ZipEntry.time field.

Webrev: http://cr.openjdk.java.net/~redestad/jdk9/8073497/webrev.0/
Bug: https://bugs.openjdk.java.net/browse/JDK-8073497

See bug for more details.

This behavior was actually the case before 8-b94, when the time field
was removed in favor of a set of FileTime fields, but when it was later
re-introduced to address some compatibility issues the conversion was
implemented in an eager fashion. This inadvertently affects VM startup
ever so little, since for every entry read via a ZipFile or ZipInputStream
we'll do a relatively expensive call creating a Date and doing timezone
conversion.

Some gains from loading fewer classes during VM startup, as well.

Thanks!

/Claes