Add a new at_shutdown queue, SHUTDOWN_FINAL.  This queue is run at splhigh() after any system dumps have completed.  SHUTDOWN_POST_SYNC isn't quite late enough for disk controllers.
Add a new at_shutdown queue, SHUTDOWN_FINAL.  This queue is run at
splhigh() after any system dumps have completed.  SHUTDOWN_POST_SYNC
isn't quite late enough for disk controllers.

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