Fix tunable and sysctl handling of the fail_on_task_timeout knob.

Reviewed by:	emax
Obtained from:	Netflix, Inc.
MFC after:	3 days
Update Mentor and Mentee Information (bofh)

Differential Revision:	https://reviews.freebsd.org/D1363
Reviewed by:	bapt
Approved by:	bapt
Clarify to explain that C99 conforming compilers don't need CMPLX*().

Discussed with: kargl@
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/userlandenhanced