Update sys/queue.h from FreeBSD
This brings sys/queue.h to the most up-to-date version from FreeBSD, incorporating 18 commits from the past 5 years (2015-02-24 - 2021-01-25): $ git log --oneline 9090a24aed70..8d55837dc133 sys/sys/queue.h share/man/man3/queue.3
Only minimal changes compared to the FreeBSD version have been applied (queue.3 -> queue.3bsd, LIBBSD prefix).