RFR: 8246272: Make use of GCLogPrecious for G1, Parallel and Serial

[Stefan Karlsson]

Hi all,

Please review this patch to turn the GC init logging into "precious" 
logging, so that those lines get dumped into the hs_err file.

https://cr.openjdk.java.net/~stefank/8246272/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8246272

Example output from a G1 hs_err file:

GC Precious Log:
  CPUs: 32 total, 32 available
  Memory: 125G
  Large Page Support: Disabled
  NUMA Support: Disabled
  Compressed Oops: Enabled (Zero based)
  Heap Region Size: 16M
  Heap Min Capacity: 16M
  Heap Initial Capacity: 2016M
  Heap Max Capacity: 30688M
  Pre-touch: Disabled
  Parallel Workers: 23
  Concurrent Workers: 6
  Concurrent Refinement Workers: 23
  Periodic GC: Disabled

I've changed the generic GCInitLogger so all GCs get these lines dumped. 
I've also added the G1 and Parallel specific lines. I can add the 
Shenandoah and Epsilon specific lines, if it is requested.

Thanks,
StefanK