RFR JDK-8060017 G1: Report heap sizing time

[Eric Caspole]

Hi everybody,

Could you review this small change to add heap expand time from the VM 
thread into the PrintGCDetails for G1 -

  https://bugs.openjdk.java.net/browse/JDK-8060017

webrev:
  http://cr.openjdk.java.net/~ecaspole/JDK-8060017/05/

The heap expand time taken on the gc threads that would happen during 
object evacuation is already accounted for into the "ObjCopy" time 
although certainly much other work also happens in that phase. But at 
this point the heap expand time on the VM thread is lost into 
unaccounted "Other" time. I started this a long time ago and forgot 
about it due to other work.
Thanks,
Eric