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)
MFC 270722:
Correct the destroy example.  The -n argument is not needed (and is not
valid).

Approved by:	re (gjb for 10)
Merge remote-tracking branch 'freebsd/stable/10' into hardened/10/aslr