RFR (S): Print GC cycle ID (+ VMOperations cleanup)

[Aleksey Shipilev]

Hi,

Let's finally have GC cycle IDs in the log:
  http://cr.openjdk.java.net/~shade/shenandoah/gc-cycle-id/webrev.01/

Prints like G1:

[5.241s][info][gc] GC(1) Pause Init-Mark 3.008ms
[5.525s][info][gc] GC(1) Concurrent marking 3076M->3152M(4096M) 283.962ms
[5.531s][info][gc] GC(1) Pause Final Mark 3152M->1148M(4096M) 4.860ms
[5.539s][info][gc] GC(1) Concurrent evacuation  1148M->1192M(4096M) 8.572ms
[7.499s][info][gc] GC(2) Pause Init-Mark 5.103ms
[7.777s][info][gc] GC(2) Concurrent marking 3084M->3250M(4096M) 277.868ms
[7.783s][info][gc] GC(2) Pause Final Mark 3250M->2460M(4096M) 5.320ms
[7.807s][info][gc] GC(2) Concurrent evacuation  2460M->2534M(4096M) 24.227ms
[8.352s][info][gc] GC(3) Pause Init-Mark 0.576ms

Testing: hotspot_gc_shenandoah

Thanks,
-Aleksey