Fix sanity error when pet ate a mimic corpse

When a pet ate a mimic corpse and started mimicking a monster,
and the user then used #wizmakemap, the sanity checker complained
about "non-mimic posing as foo" - the code was clearing the
pet eating counter, but didn't clear the appearance.

src/dog.c

@@ -733,7 +733,7 @@ keepdogs(
                unlike level change for steed, don't bother trying
                to achieve a normal trap escape first */
             mtmp->mtrapped = 0;
-            mtmp->meating = 0;
+            finish_meating(mtmp);
             mtmp->msleeping = 0;
             mtmp->mfrozen = 0;
             mtmp->mcanmove = 1;