RFR: 8204165: Filter out tests requiring class unloading when ClassUnloading is disabled

[Stefan Karlsson]

Hi all,

Please review this patch to annotate jtreg tests that require 
ClassUnloading with @requires vm.opt.final.ClassUnloading.

http://cr.openjdk.java.net/~stefank/8204165/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8204165

This @requires tag will filter out these tests when run with 
-XX:-ClassUnloading or when run with GC that doesn't support class 
unloading.

For the discussion around the introduction of the vm.opt.final tags, 
see: http://mail.openjdk.java.net/pipermail/hotspot-dev/2018-May/032586.html

Thanks,
StefanK