0.9.11.43:

	Fix bug reported by Levente Meszaros sbcl-devel 2004-04-19:
	cache filling with negative offset.
	... when precomputing cache contents, don't include classes with
		invalid wrappers.
	... irony of ironies: I'm pretty sure that there's a bug lurking
		somewhere else in any case, because the problem was
		being exhibited in the computation of a cache for
		SLOT-BOUNDP-USING-CLASS, which doesn't (or shouldn't)
		use a cacheing dfun, but instead has its own specialized
		dfun which basically calls the boundp function from the
		slot definition.  Hmm...
	... comments and minor tidying in cache.lisp