fix #2468 - killer bees without a queen

Seven year old suggestion was to have a killer bee eat royal jelly if
there was no queen around, then after a short delay it would become a
queen.  This does that, with "no queen around" being "no queen bee on
current dungeon level" and the transformation happening immediately
with the "short delay" taking place after.

Pet killer bees will target nearby royal jelly if there's no queen,
hostile killer bees will only eat it if they happen to walk on the
same spot as one.  Both types accept either tame or hostile queen bee
as an existing queen.

Killer bees eating royal jelly will drop dead if queen bees have been
genocided, and aren't smart enough to avoid the instinct to eat such
if/when that happens to be the situation.

src/monmove.c

@@ -1,4 +1,4 @@
-/* NetHack 3.6	monmove.c	$NHDT-Date: 1544442712 2018/12/10 11:51:52 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.109 $ */
+/* NetHack 3.6	monmove.c	$NHDT-Date: 1545439153 2018/12/22 00:39:13 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.110 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Michael Allison, 2006. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -254,6 +254,48 @@ struct monst *mon;
     }
 }
 
+/* killer bee 'mon' is on a spot containing lump of royal jelly 'obj' and
+   will eat it if there is no queen bee on the level; return 1: mon died,
+   0: mon ate jelly and lived; -1: mon didn't eat jelly to use its move */
+int
+bee_eat_jelly(mon, obj)
+struct monst *mon;
+struct obj *obj;
+{
+    int m_delay;
+    struct monst *mtmp = 0;
+
+    /* find a queen bee */
+    if ((mvitals[PM_QUEEN_BEE].mvflags & G_GENOD) == 0)
+        for (mtmp = fmon; mtmp; mtmp = mtmp->nmon) {
+            if (DEADMONSTER(mtmp))
+                continue;
+            if (mtmp->data == &mons[PM_QUEEN_BEE])
+                break;
+        }
+    /* if there's no queen on the level, eat the royal jelly and become one */
+    if (!mtmp) {
+        m_delay = obj->blessed ? 3 : !obj->cursed ? 5 : 7;
+        if (obj->quan > 1L)
+            obj = splitobj(obj, 1L);
+        if (canseemon(mon))
+            pline("%s eats %s.", Monnam(mon), an(xname(obj)));
+        delobj(obj);
+
+        if ((int) mon->m_lev < mons[PM_QUEEN_BEE].mlevel - 1)
+            mon->m_lev = (uchar) (mons[PM_QUEEN_BEE].mlevel - 1);
+        /* there should be delay after eating, but that's too much
+           hassle; transform immediately, then have a short delay */
+        (void) grow_up(mon, (struct monst *) 0);
+
+        if (DEADMONSTER(mon))
+            return 1; /* dead; apparently queen bees have been genocided */
+        mon->mfrozen = m_delay, mon->mcanmove = 0;
+        return 0; /* bee used its move */
+    }
+    return -1; /* a queen is already present; ordinary bee hasn't moved yet */
+}
+
 #define flees_light(mon) ((mon)->data == &mons[PM_GREMLIN]     \
                           && (uwep && artifact_light(uwep) && uwep->lamplit))
 /* we could include this in the above macro, but probably overkill/overhead */
@@ -371,7 +413,8 @@ register struct monst *mtmp;
 {
     register struct permonst *mdat;
     register int tmp = 0;
-    int inrange, nearby, scared;
+    int inrange, nearby, scared, res;
+    struct obj *otmp;
 
     /*  Pre-movement adjustments
      */
@@ -379,11 +422,10 @@ register struct monst *mtmp;
     mdat = mtmp->data;
 
     if (mtmp->mstrategy & STRAT_ARRIVE) {
-        int res = m_arrival(mtmp);
+        res = m_arrival(mtmp);
         if (res >= 0)
             return res;
     }
-
     /* check for waitmask status change */
     if ((mtmp->mstrategy & STRAT_WAITFORU)
         && (m_canseeu(mtmp) || mtmp->mhp < mtmp->mhpmax))
@@ -541,9 +583,9 @@ register struct monst *mtmp;
             }
         }
     }
-toofar:
+ toofar:
 
-    /* If monster is nearby you, and has to wield a weapon, do so.   This
+    /* If monster is nearby you, and has to wield a weapon, do so.  This
      * costs the monster a move, of course.
      */
     if ((!mtmp->mpeaceful || Conflict) && inrange
@@ -571,6 +613,14 @@ toofar:
     /*  Now the actual movement phase
      */
 
+    if (mdat == &mons[PM_KILLER_BEE]
+        /* could be smarter and deliberately move to royal jelly, but
+           then we'd need to scan the level for queen bee in advance;
+           avoid that overhead and rely on serendipity... */
+        && (otmp = sobj_at(LUMP_OF_ROYAL_JELLY, mtmp->mx, mtmp->my)) != 0
+        && (res = bee_eat_jelly(mtmp, otmp)) >= 0)
+        return res;
+
     if (!nearby || mtmp->mflee || scared || mtmp->mconf || mtmp->mstun
         || (mtmp->minvis && !rn2(3))
         || (mdat->mlet == S_LEPRECHAUN && !findgold(invent)