0.9.7.28:

0.9.7.28:
        Make MAP-ALLOCATED-OBJECTS use gencgc pagetable information to
        skip over free dynamic space regions.

        * More accurate ROOM results (previously all empty space up to
          the fake allocation pointer would get counted as conses)
        * Usually faster
        * Needed for some GC work that might get committed in the future
        * Genesify the GENCGC page size, while since it's now needed
          in Lisp