8152113: Remove _last_ditch_collection GC-cause and avoid expanding heap on Metaspace OOM
Reviewed-by: brutisso, jwilhelm

8072913: [REDO] GCCause should distinguish jcmd GC.run from System.gc()
Summary: GCCause which is caused by GC.run diagnostic command should be different from System.gc() .
Reviewed-by: jmasa, jwilhelm

8079792: GC directory structure cleanup
Reviewed-by: brutisso, stefank, david