bsd-user: Add time system call dispatch

Wire up time-related system calls in the FreeBSD syscall dispatcher:
nanosleep, clock_nanosleep, clock_gettime, clock_settime, clock_getres,
gettimeofday, settimeofday, adjtime, ntp_adjtime, ntp_gettime,
clock_getcpuclockid2, utimes, lutimes, futimes, futimesat,
ktimer_create, ktimer_delete, ktimer_settime, ktimer_gettime,
select, pselect, ppoll, kqueue, freebsd11_kevent, kevent,
setitimer, getitimer, futimens, utimensat, and sigtimedwait.

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Kyle Evans <kevans@FreeBSD.org>
Assisted-by: Claude Opus 4.6 (1M context)
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>