[9] RFR of 8073187: Unexpected side effect in Pack200

[mikhail cherkasov]

Hi all,

Bug: https://bugs.openjdk.java.net/browse/JDK-8073187
The problem is that packer changes global state( default time zone ) 
without proper synchronization:
http://hg.openjdk.java.net/jdk9/client/jdk/file/a159e5358e25/src/java.base/share/classes/com/sun/java/util/jar/pack/PackerImpl.java#l85

however javadoc says that it's save to use it in concurrent way if each 
thread has it's own packer instance:
http://hg.openjdk.java.net/jdk9/client/jdk/file/a159e5358e25/src/java.base/share/classes/java/util/jar/Pack200.java#l149

The fix isn't perfect but it the only possible solution:
1. first packer saves default time zone
2. the last set it back.

Webrev:
http://cr.openjdk.java.net/~mcherkas/8073187/webrev/src/share/classes/com/sun/java/util/jar/pack/PackerImpl.java.udiff.html

Thanks,
Mikhail.