0.7.7.20-backend-cleanup-1.8:

0.7.7.20-backend-cleanup-1.8:
	Commit PPC handling of !DEFINE-TYPE-VOPS
	... adjust interface slightly on x86
	... new MASK keyword for super-duper scary "save a couple of
		instructions" lowtag checking
	... deletia
	Tested on PPC and x86. Should now work on all architectures!