Include nss.h only when PC98 is defined.
Include nss.h only when PC98 is defined.

Pointed out by:	"Pierre Y. Dampure" <pierre.dampure@k2c.co.uk>

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