Restore KTR_CRITICAL but conditionally compile it in as KTR_SCHED.
Restore KTR_CRITICAL but conditionally compile it in as KTR_SCHED.

Requested by:	scottl, jhb

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