8235760: ZGC: Implement precise check for @require vm.gc.Z for Windows

[erik.osterlund at oracle.com]

Hi Stefan,

Looks good.

Thanks,
/Erik

On 12/11/19 1:10 PM, Stefan Karlsson wrote:
> Hi all,
>
> Please review this patch to reimplemente @require vm.gc.Z and 
> WB_IsGCSupported to use a more precise check on Windows.
>
> https://cr.openjdk.java.net/~stefank/8235760/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8235760
>
> With this patch we call into the VM and try to resolve the required 
> Windows APIs, instead of doing string comparisons on system properties.
>
> Thanks,
> StefanK