RFR 8198908: Add JVM support for preview features

[harold seigel]

Hi,

Please review this fix to implement the JVM part of JEP 12 
<https://bugs.openjdk.java.net/browse/JDK-8195734>. The changes involve 
modifications to JDK major and minor class version processing and adding 
additional logging.

Open Webrev: http://cr.openjdk.java.net/~hseigel/bug_8198908/webrev/

JBS Bug:  https://bugs.openjdk.java.net/browse/JDK-8198908

CSR:  https://bugs.openjdk.java.net/browse/JDK-8200440

This fix was tested with Mach5 tiers 1 and 2 tests and builds on all 
Mach5 platforms, with tiers 3-5 tests on Linux-x64, and with JCK-11 Lang 
and VM tests.

Thanks, Harold