Merge changes from NetBSD on humanize_number.c, 1.8 -> 1.13
Significant changes:
- rev. 1.11: Use PRId64 instead of a cast to long long and %lld to print
an int64_t.
- rev. 1.12: Fix a bug that humanize_number() produces "1000" where it
should be "1.0G" or "1.0M".  The bug reported by Greg Troxel.

PR:             [[ https://bugs.freebsd.org/118461 | 118461 ]]
PR:             [[ https://bugs.freebsd.org/102694 | 102694 ]]
Approved by:    rwatson (mentor)
Obtained from:  NetBSD
MFC after:      1 month