Typesetting fix for -r1.137.
Typesetting fix for -r1.137.

If a tail queue is empty the return value of TAILQ_LAST is not
undefined, it is NULL.

Submitted by: Ruslan Ermilov <ru@FreeBSD.org>

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