RFR(S): 8010738: G1: Output for full GCs with +PrintGCDetails should contain perm gen size/meta data change info

[John Cuthbertson]

Hi Everyone,

Can I get a couple of volunteers review these fairly straight forward 
changes? The webrev can be found at: 
http://cr.openjdk.java.net/~johnc/8010738/webrev.0/.

Summary:
At sustaining engineering's request I've added the change information 
about the metadata space to the detailed heap output for full GCs:

> 4.896: [Full GC (Allocation Failure) 512M->343M(512M), 4.3640117 secs]
>    [Eden: 0.0B(25.0M)->0.0B(97.0M) Survivors: 0.0B->0.0B Heap: 
> 512.0M(512.0M)->343.3M(512.0M)], [Metaspace: 1611K->2433K(6448K)]
>  [Times: user=5.13 sys=0.15, real=4.36 secs]

The information that gets printed mirrors that of the other collectors. 
Here's parallel GC:

> 33.245: [Full GC (Ergonomics) [PSYoungGen: 133632K->3423K(144640K)] 
> [ParOldGen: 348158K->348158K(348160K)] 481790K->351581K(492800K), 
> [Metaspace: 1612K->2433K(6448K)], 2.5788089 secs] [Times: user=9.96 
> sys=0.00, real=2.58 secs]

The information that's printed is the amount of metaspace used before 
the GC, the capacity, and the amount of reserved space.

The changes should be straight forward when this is backported to hs24 - 
namely replacing the call to MetaspaceAux::print_metaspace_change() to 
perm_gen()->print_heap_change().

Most of the changes are the result of renaming some of the fields in 
G1CollectorPolicy and the local variables in 
G1CollectorPolicy::print_detailed_heap_transition().

The included regression test just spawns a child java process to run a 
very simple system GC test program with G1 and +PrintGCDetails. The 
output of the spawned process is checked for "Metaspace".

Thanks,

JohnC