* lib/count-one-bits.h: Add comments. (From Bruno Haible.)

* lib/count-one-bits.h: Add comments.  (From Bruno Haible.)

* lib/count-one-bits.h: Don't include <limits.h>; no longer needed
given the changes below.
(COUNT_ONE_BITS): Use 'verify' rather than 'verify_true'.  Work
even on hosts that have padding bits beyond the supported 64.
(From Paul Eggert.)