Reviewed-by: coleenp, sspitsyn, mgronlun

8026948: JvmtiEnv::SetBreakpoint and JvmtiEnv::ClearBreakpoint might not work with anonymous classes
Summary: Walk methods in breakpoints for marking on stack so they aren't deallocated by redefine classes.  Use class_holder rather than class_loader to keep GC from reclaiming class owning the method.
Reviewed-by: sspitsyn, ehelin, sla

Summary: Added on_stack bit to flags.  Also MetadataMarkOnStack is used for more than JVMTI so had to be moved.
Reviewed-by: dholmes, stefank