0.8.9.28:

0.8.9.28:
	Restore buildability goodness on PPC and SPARC
	... move n-fixnum-foo-bits and so on from sparc-specific code
		to early-vm.lisp
	... while I'm at it, make the n-lowtag-bits calculated rather
		than #+ / #-
	... restore the hideous hack in ppc type-vops UGH UGH UGH
		(my brain is too slow to fix this properly)