discarding migrating objects when entering endgame

Avoid potential impossible "obfree: deleting worn object" warnings
when entering the endgame.

The code to get rid of items migrating to non-endgame levels passes
those items to obfree().  It needs to clear obj->owornmask first
because that's used for migration flags (undelivered orctown loot
has a non-zero value).

src/dog.c

@@ -886,13 +886,15 @@ discard_migrations(void)
             *oprev = otmp->nobj; /* remove otmp from migrating_objs */
             otmp->nobj = 0;
             otmp->where = OBJ_FREE;
+            otmp->owornmask = 0L; /* overloaded for destination usage;
+                                   * obfree() will complain if nonzero */
             obfree(otmp, (struct obj *) 0); /* releases any contents too */
         }
     }
 }
 
-/* return quality of food; the lower the better */
+/* returns the quality of an item of food; the lower the better;
-/* fungi will eat even tainted food */
+   fungi and ghouls will eat even tainted food */
 int
 dogfood(struct monst *mon, struct obj *obj)
 {

src/dokick.c

@@ -1433,9 +1433,10 @@ drop_to(coord *cc, schar loc, coordxy x, coordxy y)
 
 /* player or missile impacts location, causing objects to fall down */
 void
-impact_drop(struct obj *missile, /* caused impact, won't drop itself */
+impact_drop(
-            coordxy x, coordxy y,    /* location affected */
+    struct obj *missile,  /* caused impact, won't drop itself */
-            xint16 dlev)          /* if !0 send to dlev near player */
+    coordxy x, coordxy y, /* location affected */
+    xint16 dlev)          /* if !0 send to dlev near player */
 {
     schar toloc;
     register struct obj *obj, *obj2;

src/mkmaze.c

@@ -18,7 +18,7 @@ static boolean put_lregion_here(coordxy, coordxy, coordxy, coordxy, coordxy,
 static void baalz_fixup(void);
 static void setup_waterlevel(void);
 static void unsetup_waterlevel(void);
-static void check_ransacked(char *);
+static void check_ransacked(const char *);
 static void migr_booty_item(int, const char *);
 static void migrate_orc(struct monst *, unsigned long);
 static void shiny_orc_stuff(struct monst *);
@@ -228,8 +228,8 @@ fix_wall_spines(coordxy x1, coordxy y1, coordxy x2, coordxy y2)
 
             /* set the locations TRUE if rock or wall or out of bounds */
             loc_f = within_bounded_area(x, y, /* for baalz insect */
-                                        g.bughack.inarea.x1, g.bughack.inarea.y1,
+                                     g.bughack.inarea.x1, g.bughack.inarea.y1,
-                                        g.bughack.inarea.x2, g.bughack.inarea.y2)
+                                     g.bughack.inarea.x2, g.bughack.inarea.y2)
                        ? iswall
                        : iswall_or_stone;
             locale[0][0] = (*loc_f)(x - 1, y - 1);
@@ -631,7 +631,7 @@ fixup_special(void)
 }
 
 static void
-check_ransacked(char * s)
+check_ransacked(const char *s)
 {
     /* this kludge only works as long as orctown is minetn-1 */
     g.ransacked = (u.uz.dnum == mines_dnum && !strcmp(s, "minetn-1"));
@@ -641,7 +641,7 @@ check_ransacked(char * s)
 static const char *const orcfruit[] = { "paddle cactus", "dwarven root" };
 
 static void
-migrate_orc(struct monst* mtmp, unsigned long mflags)
+migrate_orc(struct monst *mtmp, unsigned long mflags)
 {
     int nlev, max_depth, cur_depth;
     d_level dest;
@@ -702,6 +702,7 @@ shiny_orc_stuff(struct monst* mtmp)
             add_to_minv(mtmp, otmp);
     }
 }
+
 static void
 migr_booty_item(int otyp, const char* gang)
 {