filesystems/zfs-stats-lite: update to 1.5

Fetch from GitHub instead of SourceForge and take maintainership.
1.5 sums the vmstat -m Memory column in bytes and, when
kstat.zfs.misc.arcstats.p is absent, reports MRU and MFU from
arcstats.mru_size and arcstats.mfu_size.

PR: 298776
Reported by: asomers
Approved by: fuz (mentor), jrm (mentor), asomers, 0mp
Reviewed by: fuz (mentor), jrm (mentor), asomers, 0mp
Differential Revision: https://reviews.freebsd.org/D59944