RFR: 8218732: SA: Resolves ZPageAllocator::_physical incorrectly

[Stefan Karlsson]

Hi all,

Please review this small patch to resolve ZPageAllocator::_physical as a 
value object instead of a pointer.

https://cr.openjdk.java.net/~stefank/8218732/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8218732

This fixes the Heap Parameters view.

Thanks,
StefanK