0.8.0.29:

	Port fix to PCL from Gerd Moellmann regarding metacircles:
	there was a hole in the metacircularity detection of legacy PCL,
	which is filled by bypassing ordinary slot access for standard
	classes in cache miss handling when doing so would lead to
	another cache miss.
	... *CACHE-MISS-VALUES-STACK* and *STANDARD-SLOT-LOCATIONS* (not
	audited for threadsafety)