make_room
void *room = make_room(mem_start, mem_end, 4, 4); \
namep = make_room(mem_start, mem_end, MAX_PROPERTY_NAME, 1);
namep = make_room(mem_start, mem_end, l+1, 1);
valp = make_room(mem_start, mem_end, l, 4);
valp = make_room(mem_start, mem_end, 4, 4);
hdr = make_room(&mem_start, &mem_end,
rsvmap = make_room(&mem_start, &mem_end, sizeof(mem_reserve_map), 8);
namep = make_room(&mem_start, &mem_end, 16, 1);