(sct_pstage, sct_ptime, shp_pstage, shp_ptime, lnd_pstage, lnd_ptime):

Use `short' instead of `unsigned short'.  With variables, plague stage
and time were stored unsigned and used signed, which worked.  Removal
of variables dropped the conversion to signed, which broke
plague_people() (plague.c rev. 1.6): stage didn't progress correctly
due to catastrophic underflow of time.

src/lib/update/ship.c

@@ -115,7 +115,7 @@ upd_ship(struct shpstr *sp, int etus,
 {
     struct sctstr *sectp;
     struct mchrstr *mp;
-    u_short pstage, ptime;
+    int pstage, ptime;
     int oil_gained;
     int max_oil;
     int max_food;