0.8.5.22:

0.8.5.22:
	gencgc cleanup:
	... Replaced all (but one) literal 4096 (and 0xfff) with
	PAGE_BYTES constant. I think the ones I changed were all about
	page size, but I added a FIXME where I was unsure. There is
	one bare 4096 left, but that's not a page size, I think.
	... Removed gencgc.h, because it wasn't actually needed and
	mostly duplicated stuff from gencgc-internal.h