MFC r297476:Add a cross reference to ktrace(2).Obtained from: CheriBSD (9cb420d6b7f04c1b7d2006180b80932e5d3fe50e)Sponsored by: DARPA, AFRL
MFC 270674:Clarify that the -c argument clears the list of tracepoints specified by-t (it does not clear all tracepoints).Approved by: re (gjb for 10)