RFR: 8232651: Add implementation of os::processor_id() for Windows

[Stefan Karlsson]

Hi all,

Please review this patch to add an implementation of os::processor_id() 
for Windows.

https://cr.openjdk.java.net/~stefank/8232651/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8232651

We need an implementation of this function on Windows, to be able to run 
ZGC there.

Note that GetCurrentProcessorNumber only "returns the processor number 
within the processor group to which the logical processor is assigned". 
AFAICT, there's no support for multi-groups in HotSpot, and therefore 
this seems like an adequate function to use.

See this page for more information about processor groups:
https://docs.microsoft.com/en-us/windows/win32/procthread/processor-groups

Thanks,
StefanK