RFR (L) 8208242: Add @requires to vmTestbase/gc/g1 tests

[Kim Barrett]

> On Aug 2, 2018, at 2:29 PM, JC Beyler <jcbeyler at google.com> wrote:
> 
> Hi all,
> 
> I added the fact that the test requires G1 and that unloading is not disabled via 3 new @requires tags.
> 
> Would someone review the test changes for me?
> Webrev: http://cr.openjdk.java.net/~jcbeyler/8208242/webrev.00/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8208242
> 
> Thanks for your help,
> Jc
> 
> Ps: I merged the "add a requires for the unloading"  from https://bugs.openjdk.java.net/browse/JDK-8208206 into JDK-8208242 and updated the text so that I don't do another trivial webrev for all these tests (hopefully)

Looks good, and despite it size, trivial.