When freeing session, restore its ID after zeroing memory.
When freeing session, restore its ID after zeroing memory.

Bug tracked down by:	Patrick Lamaiziere <patfbsd@davenulle.org>

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