This will only work if the caller already handles SIGSYS, which is not
always the case.
Address this by checking osreldate instead. Note that because there
was not __FreeBSD_version bump when the system call was added, use
1200061 (r332100) which is the first bump after the introduction of
the system call.
PR: 230762
Reported by: Jenkins via Mark Millard
Reviewed by: cem
Differential Revision: https://reviews.freebsd.org/D16807