MFV: libucl: Update to 0.9.2
- Add FREEBSD-upgrade instructions
- Add FREEBSD-Xlist file
- Remove all unnecessary files which are not required for in-tree build
Approved by: bapt
Differential Revision: https://reviews.freebsd.org/D50472
Event: Oslo Hackathon 202508
Sponsored by: The FreeBSD Foundation
(cherry picked from commit 2326db40a1d2dd98631d70aae200ca52575139fb)