RFR: Report how much we have failed to allocate during Allocation Failure

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/alloc-report-fail-size/webrev.01/

This adds the message about the failed allocation size into the GC log. With free set state
printout, this makes an easy way to spot fragmentation problems. Sample output with completely
depleted free set:

[4.884s][info][gc      ] GC(1) Failed to allocate 4K for evacuation
[4.884s][info][gc      ] GC(1) Cancelling concurrent GC: Allocation Failure During Evac
[4.886s][info][gc      ] GC(1) Concurrent evacuation 8749M->10239M(10240M) 97.007ms
[4.886s][info][gc,ergo ] Free set: Used: 1499M of 1499M, Regions: 0 mutator, 0 collector
[4.886s][info][gc,ergo ] Free set: Mutator view: Max regular: 0K, Max humongous: 0K, External frag:
0%, Internal frag: 0%
[4.886s][info][gc,ergo ] Free set: Collector view: Max regular: 0K

Testing: hotspot_gc_shenandoah

Thanks,
-Aleksey