In preparation for deprecating CIRCLEQ macros in favor of TAILQ macros which provide the same functionality and are a bit more efficient, convert use of CIRCLEQ's in netgraph PPP code to TAILQ's.
In preparation for deprecating CIRCLEQ macros in favor of TAILQ
macros which provide the same functionality and are a bit more
efficient, convert use of CIRCLEQ's in netgraph PPP code to TAILQ's.

Reviewed by:	Archie Cobbs <archie@dellroad.org>

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