- Export HZ value via kern.hz sysctl (this is the same name as for the   loader tunable). - Document other sysctls in this file and also mark them as loader tunable   via CTLFLAG_RDTUN flag.
- Export HZ value via kern.hz sysctl (this is the same name as for the
  loader tunable).
- Document other sysctls in this file and also mark them as loader tunable
  via CTLFLAG_RDTUN flag.

Reviewed by:	roberto

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase