hp malloc: fix the hash size macros

	* the old ones actually led to bad memory accesses within hp_malloc()
(cherry picked from commit faaca742a06d5a1e5f8925a1e95cfafcdd85c709)
hp malloc: reduce the built-in maximum split factor

	* dividing the list into too many smaller ones may actually hurt performance
	* this also reduces the minimum pkg and shm consumption by 3.4MB when
	  enabling HP_MALLOC
(cherry picked from commit 7d302c18fbd6c4c4d7af64aeddb1e9c65b6c9fc3)