Fix couple cases of boulders over pits

When a zombie claws itself out of the ground.
When a polymorph is zapped on a pile of objects over a pit,
and one of them turns into a boulder.

src/do.c

@@ -2185,6 +2185,7 @@ revive_corpse(struct obj *corpse)
                     Soundeffect(se_scratching, 50);
                     You_hear("scratching noises.");
                 }
+                fill_pit(mtmp->mx, mtmp->my);
                 break;
             }
             /*FALLTHRU*/

src/zap.c

@@ -2450,6 +2450,8 @@ bhitpile(
     if (hidingunder) /* pile might have been destroyed or dispersed */
         maybe_unhide_at(tx, ty);
 
+    fill_pit(tx, ty);
+
     return hitanything;
 }