RFR: 8247759: ZGC: Replace ZGC specific array implementations with GrowableArray

[Stefan Karlsson]

Hi all,

Please review this patch to replace ZGC specific array implementations 
with usages of GrowableArray.

https://cr.openjdk.java.net/~stefank/8247759/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8247759

Testing: tier1-tier7. I've been running this patch together with 
unrelated changes for a while now.

Thanks,
StefanK