procctl: actually require debug privileges over target
for state control over TRACE, TRAPCAP, ASLR, PROTMAX, STACKGAP,
NO_NEWPRIVS, and WXMAP.
Reported by: emaste
Reviewed by: emaste, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D32513