net-p2p/{lib,r}torrent: Update to 0.16.23

This release includes various bugfixes and minor improvements as part of
a stable series of releases.

ChangeLog: https://github.com/rakshasa/rtorrent/releases/tag/v0.16.23
MFH: 2026Q3
(cherry picked from commit 2bab20852d1715a94be81dcd2aca69bcb12e8bc0)