Don't interrupt tin opening if being slimed and tin is chameleon

Another SliceHack feature. It's possible for you to eat the chameleon
tin and turn into a fiery monster that burns off the slime in its
natural form, either extremely luckily at random or if you have
polymorph control.

doc/fixes37.0

@@ -115,6 +115,7 @@ auto-id scroll of remove curse when a known buc-state was changed
 demon lords hate Demonbane
 pets avoid eating shapeshifter corpses unless starving or nearly feral
 blessed scroll of teleportation gives a single controlled teleport
+allow opening a tin without interruption if slimed
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository

src/eat.c

@@ -3357,8 +3357,10 @@ int threat;
     case STONED:
         return (boolean) (mndx >= LOW_PM
                           && (mndx == PM_LIZARD || acidic(&mons[mndx])));
-    /* no tins can cure these (yet?) */
+    /* polymorph into a fiery monster */
     case SLIMED:
+        return (boolean) (mndx == PM_CHAMELEON);
+    /* no tins can cure these (yet?) */
     case SICK:
     case VOMITING:
         break;