clear a couple of new warnings

mondata.c:198:17: warning: unused variable 's' [-Wunused-variable]
    const char *s;
                ^
1 warning generated.

steed.c:43:17: warning: unused variable 's' [-Wunused-variable]
    const char *s;
                ^
1 warning generated.

src/steed.c

@@ -40,7 +40,6 @@ struct obj *otmp;
     struct monst *mtmp;
     struct permonst *ptr;
     int chance;
-    const char *s;
 
     if (!u_handsy())
         return 0;