[! HAVE_INTTYPES_H && HAVE_STDINT_H] Include <stdint.h>.

[! HAVE_INTTYPES_H && HAVE_STDINT_H] Include <stdint.h>.
(UINTMAX_MAX) [!defined UINTMAX_MAX]: New macro.
(PROPAGATE_ALL_ONES): Work even if X is unsigned and narrower than
int.  Work more efficiently if X is the same width as uintmax_t.
Do not compare X to -1, to avoid bogus compiler warning.
(get_fs_usage): (uintmax_t) -1 -> UINTMAX_MAX to avoid a cast.
Don't assume that f_frsize and f_bsize are the same type.