RFR(XS): 8210259: [testbug] IncompatibleOptions.java fails if VM configured without ZGC

[Per Liden]

On 08/31/2018 01:58 PM, Lindenmaier, Goetz wrote:
> Hi,
> 
> could I please get reviews for this tiny fix?
> http://cr.openjdk.java.net/~goetz/wr18/8210259-fixNoZGCError/webrev.01/
> 
> The testcase enabling ZGC is protected by (Platform.isLinux() && Platform.isX64()).
> Thus, the test fails if the VM is compiled without ZGS on linuxx86_64.
> Fix: use GC.Z.isSupported()

Looks good!

(In theory we should have this test for all other GCs too, since they 
can also be compiled out, and it would be nice if testing passed 
anyway... but let's not go there now...)

/Per