0.7.3.9:

0.7.3.9:
	merged NJF "PCL question" patch (sbcl-devel 2002-05-02)
	merged NJF "PCL cleanups" patch (sbcl-devel 2002-05-02)
	problem: CACHE-NUMBER-VECTOR-REF (converted from macro to
		inline function in NJF patches above) needs to be
		SETFable, so it'd need two functions, not just one,
		which is a little too much trouble, so I just reverted
		that part of the patch.
	deleted apparently-unused CLASS-NO-OF-INSTANCE-SLOTS