another impossible() update for dog_eat()

src/dogmove.c

@@ -313,12 +313,15 @@ dog_eat(struct monst *mtmp,
         /* It's a reward if it's DOGFOOD and the player dropped/threw it.
            We know the player had it if invlet is set. -dlc */
         if (dogfood(mtmp, obj) == DOGFOOD && obj->invlet) {
+            int prior_apport = edog->apport;
+
             edog->apport += (int) (200L / ((long) edog->dropdist + svm.moves
                                            - edog->droptime));
             if (edog->apport <= 0) {
-                impossible("dog_eat: pet apport <= 0 (%d, %d, %ld, %ld, %ud, %ud)",
+                impossible("dog_eat: pet apport <= 0 (%d, %d, %ld, %ld, %d, %ud, %ud)",
                             edog->apport, edog->dropdist, edog->droptime,
                             svm.moves,
+                            prior_apport,
                            /* check whether edog struct got clobbered;
                               these two values should always match if
                               edog content is still intact */