[net.sources.games] Fix for hack 1.0.3 engrave bug

kelem@aero2.ARPA (Steve Kelem ATW) (01/21/87)

Problem: Hack 1.0.3 dumps core if you try to "engrave(write)" something
on the floor with your finger.  This is caused by dereferencing a nil pointer.
This is tolerable on a Vax, but not on a Sun.

Fix: The following change in the file "engrave.c" will avoid dereferencing
a nil pointer.

144c144
< 	if(otmp->otyp == WAN_FIRE && otmp->spe) {
---
> 	if(otmp && otmp->otyp == WAN_FIRE && otmp->spe) {