[lworld] Add LoadableDescriptors to comments for class loading

The comments around resolve_with_circularity_detection say that its for super classes and interfaces but the valhalla code will add LoadableDescriptors to this. Some comments will need to be updated when the mainline is merged in:

Pointed out by David Holmes in code review for JDK-8336919:

Line 387: // Must be called for any superclass or superinterface resolution

Line 427: // If klass is already loaded, just return the superclass or superinterface.

Line 471: // Resolve the superclass or superinterface, check results on return