8155672: Remove instanceKlassHandles and KlassHandles
Summary: Summary: Use unhandled pointers for Klass and InstanceKlass, remove handles with no implementation.
Reviewed-by: dholmes, lfoltan, vlivanov, sspitsyn

8065331: Add trace events for failed allocations
Reviewed-by: brutisso, ehelin

8145752: Fix include guards in GC code
Reviewed-by: mgerdin, stefank

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